CN113043604B - Induction welding method for thermoplastic composite material with high welding strength and implanted layer - Google Patents
Induction welding method for thermoplastic composite material with high welding strength and implanted layer Download PDFInfo
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/04—Dielectric heating, e.g. high-frequency welding, i.e. radio frequency welding of plastic materials having dielectric properties, e.g. PVC
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C69/00—Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore
- B29C69/02—Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore of moulding techniques only
Abstract
The invention relates to an induction welding method for a thermoplastic composite material with high welding strength and an implanted layer, which is characterized in that a SPEEK @ CNT/CF/thermoplastic resin composite film is used as the implanted layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength; the preparation method of the SPEEK @ CNT/CF/thermoplastic resin composite film comprises the following steps: firstly blending SPEEK modified CNT and a thermoplastic resin matrix and pressing the mixture into a SPEEK @ CNT/thermoplastic resin film, and then preparing the SPEEK @ CNT/thermoplastic resin film and a CF two-dimensional fabric with desized surface through laminating and mould pressing to obtain the SPEEK @ CNT/CF/thermoplastic resin composite film; the single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/thermoplastic resin composite film implantation layer is 38-49 MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 30-39 MPa. The invention solves the problems of lower single lap shear strength and poorer fatigue resistance of the welded joint prepared by the method in the prior art.
Description
Technical Field
The invention belongs to the technical field of thermoplastic composite materials, and relates to an induction welding method for a thermoplastic composite material with high welding strength and an implanted layer.
Background
In recent years, thermoplastic resin-based composite materials have a very fast development speed, and have remarkable advantages compared with thermosetting materials, such as recyclability, good high-temperature service performance, no solvent in the preparation process, high impact toughness and the like, so that the thermoplastic resin-based composite materials become important directions for the cost reduction and the high performance of civil aviation composite materials. Compared with thermosetting materials, the manufacturing cost can be reduced by more than 30%. This will revolutionize the manufacturing of composite materials. At present, boeing, air passengers and the like are all developing related technologies vigorously. The materials applied to the civil aircraft structural part manufacturing are mainly continuous Carbon Fiber (CF) reinforced polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyether ketone (PEKK) and other thermoplastic composite materials.
The thermoplastic composite material can still be melted after the molding is finished, so that the thermoplastic parts can be connected by adopting a method of melting again and applying pressure, namely welding of the thermoplastic composite material. Compared with the common riveting and gluing technology in the field of thermosetting composite materials, welding is a more economical, rapid and reliable connecting technology, and meanwhile, the weight reduction target can be realized, so that the application prospect is wide. At present, the welding technologies commonly used for thermoplastic composite materials include resistance welding, ultrasonic welding, laser welding and induction welding, and the four welding technologies have different principles. The induction welding technology is considered as the welding mode of thermoplastic composite materials with the most development prospect due to the advantages of small size, quickness, flexibility and the like. The principle is as follows: a coil having an alternating electric field in a certain shape is provided in the vicinity of a work to be welded, the alternating electric field induces an alternating magnetic field, and if a conductive loop exists in a region to be welded, an internal eddy current is induced, and a thermoplastic resin in the region to be welded is melted and joined into a whole by heat generation of electric current.
There are two main types of methods for CF reinforced composite induction welding: 1) the implanted layer is not added, and the CF is heated by the conductivity of the CF; 2) an inductive implant conductor is added.
In the first category of methods, although the CF itself may be conductive, a serious problem arises if the CF reinforced composite is directly induction welded, since the magnetic induction is greater the closer the coil is to the coil: when the surfaces to be welded are not yet melted, the surfaces adjacent to the coil are already thermally burned. Researchers, including the group of the present inventors, have done a lot of work to this end, such as lowering the surface temperature by air cooling, water cooling, heating a heat conducting plate, etc., in an attempt to move the highest temperature surface from the surface to the bonding surface. However, we have found with finite element calculations that it is difficult to lock the highest temperature face to the weld face, and the highest temperature point tends to occur somewhere near the surface. This means that if the composite material is welded successfully, the temperature of the resin inside a part of the composite material inevitably exceeds the temperature of the welding surface, and the resin such as PPS, PEEK, PEKK, etc. with a narrow processing temperature window is easily exposed to the risk of degradation, crosslinking, etc. due to overheating. Although the joint strength is not affected, the internal structure and the strength of the composite material are damaged, and more importantly, the surface is difficult to perceive, so that the application risk of the composite material is realized. Meanwhile, the method wastes a large part of energy consumption and reduces the production efficiency.
In contrast, therefore, the second method is more advocated, i.e. a layer of high conductivity induction conductor is implanted near the area to be welded, which acts to lock the highest temperature surface to the surface to be welded. In such methods, the prior art is to implant various metal conductors, such as copper mesh, stainless steel mesh, nickel-plated carbon fiber, silver nanowire, silver nanoparticle, magnetite (Fe)3O4) Nanoparticles, and the like. The weaknesses of the prior art are that: the metal mesh or nickel-plated carbon fiber has low single Lap Shear Strength (LSS) of the welded joint, generally lower than 25MPa, and poor fatigue resistance due to poor interface between metal and thermoplastic resin; and the silver nanowires, silver nanoparticles and the like are difficult to form a continuous reinforcing network, so that the final welding strength is not high, and the single lap shear strength LSS is usually lower than 28 MPa. In recent years, there has been a Development of nano/micro hybrid sheet for indexing applications, dr
Kaiserslauter, 2016.) incorporation of carbon nanotube CNTs with similar surface chemistry to CF but finer diameter, higher electrical conductivity into a nickel-plated short carbon fiber filled PPS and PP (polypropylene) composite achieves relatively uniform induction heating, but is not enhanced for continuous CF, and does not give weld strength to the weld.
Disclosure of Invention
The invention aims to solve the problems of lower single lap shear strength and poorer fatigue resistance of a welded joint prepared by the method in the prior art, and provides an induction welding method for a thermoplastic composite material containing an implanted layer with high welding strength.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the method for induction welding the implanted layer-containing thermoplastic composite material with high welding strength comprises the steps of taking a SPEEK @ CNT/CF/thermoplastic resin composite film as the implanted layer, and carrying out induction welding on the Carbon Fiber (CF) reinforced thermoplastic composite material to obtain a thermoplastic composite material connecting piece with high welding strength;
the preparation method of the SPEEK @ CNT/CF/thermoplastic resin composite film comprises the following steps: mixing SPEEK (sulfonated polyether ether ketone) modified CNT (carbon nano tube) (marked as SPEEK @ CNT) with a thermoplastic resin matrix, pressing the mixture into a SPEEK @ CNT/thermoplastic resin film, and then preparing the SPEEK @ CNT/thermoplastic resin film and a CF two-dimensional fabric with the surface being desized into a SPEEK @ CNT/CF/thermoplastic resin composite film through lamination and mould pressing; if the SPEEK @ CNT/thermoplastic resin matrix blend is used alone as an implant, the electrical conductivity and mechanical strength are far from sufficient, and a continuous CF two-dimensional fabric must be added to match the CF reinforced composite to be welded.
The single Lap Shear Strength (LSS) of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/thermoplastic resin composite film implanted layer is 38-49 MPa (tested by using a universal tester, according to the test standard of ASTM D5868, the welding strength is characterized by the LSS index), and the LSS of the connecting piece is 30-39 MPa after 30 ten thousand shear direction tensile fatigue tests (load is 1000N, and loading frequency is 2 Hz).
As a preferred technical scheme:
the thermoplastic composite material with high welding strength containing implant layer induction welding method as described above, the resin matrix in the CF reinforced thermoplastic composite material is PPS (polyphenylene sulfide), PEEK (polyether ether ketone), or PEKK (polyether ketone), and the CF is in the form of plain weave, satin weave, twill weave, or unidirectional tape.
The induction welding method of the thermoplastic composite containing implant layer having high welding strength as described above, the resin matrix in the SPEEK @ CNT/CF/thermoplastic resin composite film is PPS, PEEK or PEKK, preferably the same as the resin matrix to be welded to the CF reinforced thermoplastic composite.
The method for induction welding the implanted layer of the thermoplastic composite material with high welding strength comprises the following steps of: slowly adding dried PEEK powder into 98wt% concentrated sulfuric acid at room temperature according to the proportion of 0.01-0.3 g/ml, stirring until the powder is completely dissolved, heating the solution to 50-55 ℃, stirring for 1-5 h, cooling to room temperature, slowly adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and completely drying in a vacuum oven to obtain the product SPEEK.
The method for induction welding the implanted layer of the thermoplastic composite material with high welding strength comprises the following steps: and ultrasonically dispersing the CNT and the SPEEK in a solvent for 5-20 min to prepare a stable CNT/SPEEK suspension, centrifugally collecting solid components in the suspension, and drying until the water content is less than 0.5wt% to obtain the SPEEK modified CNT. If dried to a moisture content of greater than 0.5 wt.%, excessive moisture can introduce the possibility of degrading the resin during subsequent molding processes, or create bubbles that reduce material strength. When the SPEEK @ CNT content is too low, a conductive network cannot be formed inside the thermoplastic resin matrix, and the conductivity of the blend cannot reach a required value; if the SPEEK @ CNT content is too large, the CNT tends to agglomerate in the resin, and the strength of the implant material is significantly reduced.
The method for induction welding the implanted layer of the thermoplastic composite material with high welding strength comprises the steps of modifying the CNT into carboxyl multi-wall CNT, wherein the viscosity average molecular weight of SPEEK is 30000-60000, the solvent of a CNT/SPEEK suspension is dimethyl formamide (DMF) or dimethyl sulfoxide (DMSO), the concentration of the CNT in the CNT/SPEEK suspension is 0.05-0.1 wt%, and the concentration of the SPEEK in the CNT/SPEEK suspension is 1.5-2.5 wt%. The sulfonic acid group on the SPEEK can form double hydrogen bonds with the carboxyl group on the CNT, and can carry out heat-resistant high-molecular surface modification on the CNT, so that the CNT can be well dispersed in the thermoplastic resin matrix in the subsequent step. If the concentration of the SPEEK solution is too low, the amount of SPEEK strongly interacting with the CNT surface is too small, and the modification effect is insufficient; the SPEEK solution concentration cannot be too high because although SPEEK has a similar chemical structure and a good compatibility with the thermoplastic resin matrix to be used later, the SPEEK is two different substances, and the SPEEK molecular weight is relatively low, the SPEEK is actually similar to the interface layer of the CNT and the thermoplastic resin matrix, if the SPEEK solution concentration is too high, the interface transition layer is too thick, and the mechanical strength of the CNT/CF/thermoplastic resin film to be prepared later is reduced. If the content of the CNT is too low or the ultrasonic time is too long, the efficiency of the surface modification process is too low, and the energy consumption is wasted; if the content of the CNT is too high or the ultrasonic dispersion time is too short, the CNT is insufficiently dispersed and agglomerated, the probability of strong interaction between the surface and the SPEEK is reduced, and the surface modification effect is not good. If the SPEEK molecular weight is too small, the mechanical strength of the CNT/CF/thermoplastic resin film to be prepared later is too low, and if the SPEEK molecular weight is too high, it is difficult to dissolve in DMF or DMSO.
In the induction welding method for the implanted layer-containing thermoplastic composite material with high welding strength, the SPEEK modified CNT and the thermoplastic resin matrix are blended in a mode of mechanically blending solids by a ball mill and then melt blending by twin-screw extrusion; the thickness of the SPEEK @ CNT/thermoplastic resin film is 60 to 160 μm; if the film is too thin, the film cannot completely permeate into the CF fabric and can remove the original air in the CF fabric, so that the porosity of the implanted conductor is high, and the mechanical strength of the joint is influenced; if the film is too thick, the CF fabric layer cannot play a sufficient reinforcing role at the joint, and only the resin bears the force under the action of external shearing force, so that the shearing strength of the joint is too low.
The thermoplastic composite material containing implant layer induction welding method having high welding strength as described above, the CF two-dimensional fabric being in the form of plain, satin or twill;
the method for desizing the surface of the CF two-dimensional fabric comprises the steps of refluxing the CF two-dimensional fabric with acetone for 2-4 hours at the temperature of 40-80 ℃; the original sizing agent on the surface of the commercial CF fabric is removed, because the main component of the part is epoxy resin, the part can resist the temperature lower than the processing temperature of the induction welding of the thermoplastic composite material, and if the sizing agent is not removed, bubbles are formed in the welding, and the joint strength is reduced. When the temperature is lower than 40 ℃ or less than 2h, the pulp is removed insufficiently and the pulp remains; the temperature is higher than 80 ℃ or exceeds 4 hours, so that potential safety hazards exist, and energy consumption is wasted;
the lamination molding is to place two SPEEK @ CNT/thermoplastic resin films on two sides of a CF two-dimensional fabric with the surface thereof being de-sized respectively, lay the two-dimensional fabric in a mold flatly and perform hot press molding.
According to the induction welding method for the thermoplastic composite material containing the implanted layer with high welding strength, the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 2-8 min, wherein the molding pressure is 0.5-2 MPa, the molding temperature is T1-T2, the molding time is 5-10 min, and the cooling rate is 1-70 ℃/min;
when the resin film is made of PPS, T1 is 310 ℃, and T2 is 350 ℃;
when the resin film is made of PEEK, the T1 is 370 ℃, and the T2 is 420 ℃;
when the resin film is PEKK, T1 is 350 ℃ and T2 is 400 ℃.
The method for induction welding the implant-containing layer of the thermoplastic composite material with high welding strength comprises the following specific steps: cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust clean and drying by using acetone, and wiping the acetone to remove impurities on the surfaces of the sample strips; then, the SPEEK @ CNT/CF/thermoplastic resin composite film is placed between an upper welding sample strip and a lower welding sample strip, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, adjusting the frequency of the current generator to be 20-40 kHz, adjusting the output power of the power supply to be 20-40 kW, and after induction heating for 0.8-2 min, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength. The induction coil is connected with alternating current, an alternating magnetic field is generated nearby, eddy current induction current is generated in the SPEEK @ CNT/CF/thermoplastic resin composite film which is arranged right below the induction coil, the film layer is heated and melted, high temperature is conducted to two adjacent areas to be welded, the thermoplastic resin matrix in the areas to be welded is also melted, and the three parts of melted resin are fused together under atmospheric pressure and become an integral solid in the cooling process. If the welding frequency is too low, the temperature of the laminated plate is too slow and cannot reach the melting point of the resin, if the welding frequency is too high, the skin effect is easy to generate, and the surface of one side, close to the induction coil, of a sample to be welded is easy to degrade and discolor; if the power of the power supply is too small or the induction heating time is too short, the temperature of the area to be welded is increased too slowly, and even the temperature cannot be increased to the required resin melting temperature; if the output is too high or the heating time is too long, the resin temperature is difficult to control, and the upper limit of the processing window is easily exceeded, so that the surface is blackened or burned. By adopting the high-power pulse intermittent electrifying mode, the surface of the composite material can be accelerated to dissipate heat in an intermittent period (in a non-electrifying time period), and the temperature change of the area to be welded is not obviously influenced, because the area to be welded is positioned in the center, the heat dissipation is much slower than the surface.
The principle of the invention is as follows:
the prepared SPEEK @ CNT/CF/thermoplastic resin composite film is used as an implantation layer of the thermoplastic composite material for induction welding. The main conductive material, i.e., the component capable of generating induced current, is CF, which has a diameter (about 7 μm) much smaller than the diameter (usually over 100 μm) of the wires in the metal mesh (e.g., copper mesh, stainless steel mesh, etc.) used as the main current for the induction welding implant layer. Thus, the total area of the interface between these implanted foreign bodies (CF) and the thermoplastic resin matrix of the composite material is much larger than when using a metallic mesh of the main implanted layer; at the same time, the gaps between adjacent CFs (to be filled by the thermoplastic resin matrix) are much smaller than the gaps in the metal mesh. These two factors will result in a weld joint strength (single lap shear strength) that is substantially higher when using CF fabric than when using expanded metal. Since CF exists in the form of continuous fibers, the strength of the implanted layer itself, and the strength of the solder joint (single lap shear strength) will also be higher compared to other metal-based implanted layers, such as nano-silver particles or nano-silver wires. The doping of SPEEK modified CNTs in the matrix of the implanted layer can, on the one hand, produce a nano-effect by good dispersion of the CNTs, further enhancing the joint strength, and, on the other hand, can increase the conductivity of the implanted layer, so that the induced current strength generated by the implanted layer exceeds that of CF fabrics in the samples to be welded that are closer to the coil (because those fabrics have no CNTs, the conductivity is relatively poor). The latter has the advantage that overheating and burning of the side of the sample to be welded which is close to the induction coil can be avoided. The principle of modifying the CNT by using the SPEEK is that hydrogen bonds are formed by a sulfonic acid group in the SPEEK and a hydroxyl group on the surface of the CNT and a carboxyl group, so that the SPEEK can be firmly coated on the surface of the CNT; meanwhile, the similar compatibility of the SPEEK and a thermoplastic matrix (PEEK, PPS or PEKK) and pi-pi interaction generated by a large number of benzene rings are utilized to obtain the strong interaction of the SPEEK and the thermoplastic matrix, so that the SPEEK @ CNT can be well dispersed in the thermoplastic matrix, and the high strength and the high conductivity of the implanted layer and the welding joint are brought.
Has the advantages that:
(1) since the CF diameter is much smaller than the metal diameter and exists as a continuous CF, the self-strength of the implanted layer with CF as the main component and the resulting single lap shear strength of the welded joint are higher than when using a metal-based implanted layer. The single Lap Shear Strength (LSS) is 38-49 MPa (tested by using a universal tester according to ASTM D5868 test standard);
(2) compared with a metal implant layer, the pure carbon implant layer has higher fatigue resistance, and the LSS of the connecting piece is 30-39 MPa after 30 ten thousand shear direction tensile fatigue tests (load is 1000N and loading frequency is 2 Hz);
(3) compared with an implanted layer which does not use an implanted layer or uses a common CF fabric as a conductor, the method can lock the highest temperature surface in the welding process as the welding surface, thereby avoiding the phenomenon of overheating and scorching on one side close to the induction coil in a sample to be welded, because the conductivity of the implanted layer can be improved by the introduction and good dispersion of the CNT, and the induced current intensity generated by the implanted layer is higher;
(4) the invention adopts the pure carbon implantation layer and is expected to eliminate the problems of easy electrochemical corrosion and the like which are possibly caused when the metal implantation layer is adopted.
Detailed Description
The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Example 1
The induction welding method of the thermoplastic composite material with high welding strength and the implanted layer comprises the following specific steps:
(1) the SPEEK is prepared by the sulfonation reaction of PEEK and concentrated sulfuric acid, and specifically comprises the following steps: slowly adding dried PEEK powder into 98wt% concentrated sulfuric acid at 23 ℃ according to the proportion of 0.01g/ml, stirring until the powder is completely dissolved, heating the solution to 50 ℃, stirring for 5h, cooling to 23 ℃, slowly adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and drying to obtain SPEEK with the viscosity average molecular weight of 30000;
(2) preparation of SPEEK modified CNTs, specifically: ultrasonically dispersing CNT and SPEEK in DMF for 5min to prepare CNT/SPEEK suspension, centrifuging to collect solid components in the suspension, and drying to water content of 0.4 wt% to obtain SPEEK modified CNT; wherein the CNT is multi-wall CNT modified by carboxyl, the concentration of the CNT in the CNT/SPEEK suspension is 0.05 wt%, and the concentration of the SPEEK is 1.5 wt%;
(3) mechanically blending the SPEEK modified CNT with PPS in a mass ratio of 1:100 by adopting a ball mill, then performing melt blending by twin-screw extrusion, and pressing to form a SPEEK @ CNT/PPS film with the thickness of 60 mu m; wherein the mechanical blending time is 2min, the melt blending temperature is 310 ℃, and the time is 15 min;
(4) preparing the SPEEK @ CNT/CF/PPS composite film by laminating and molding the SPEEK @ CNT/PPS film and the plain-woven CF two-dimensional fabric with the surface being de-sized; wherein, the method for desizing the surface of the CF two-dimensional fabric is to reflux the CF two-dimensional fabric with acetone for 2h at 40 ℃; the lamination molding is to place two SPEEK @ CNT/PPS films on two sides of a CF two-dimensional fabric with the surface thereof being de-sized respectively, lay the two films in a mold flatly and perform hot press molding; the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 2 min; the molding temperature is 310 ℃, and the molding pressure is 0.5 MPa; the molding time is 10min, and the cooling rate is 1 ℃/min;
(5) the SPEEK @ CNT/CF/PPS composite film is used as an implantation layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength; wherein the CF is in the form of plain weave, and the resin matrix of the CF reinforced thermoplastic composite material is PPS; the specific process of induction welding is as follows: firstly, cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust with acetone, and drying; then, the SPEEK @ CNT/CF/PPS composite film is placed between an upper welding sample strip and a lower welding sample strip, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, adjusting the frequency of the current generator to be 20kHz, adjusting the output power of the power supply to be 20kW, and after induction heating for 0.8min, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength.
The single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/PPS composite film implanted layer is 38MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 30 MPa.
Example 2
The induction welding method of the thermoplastic composite material with high welding strength and the implanted layer comprises the following specific steps:
(1) the SPEEK is prepared by the sulfonation reaction of PEEK and concentrated sulfuric acid, and specifically comprises the following steps: slowly adding dried PEEK powder into 98wt% concentrated sulfuric acid at 24 ℃ according to the proportion of 0.05g/ml, stirring until the powder is completely dissolved, heating the solution to 51 ℃, stirring for 4h, cooling to 24 ℃, slowly adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and drying to obtain SPEEK with the viscosity average molecular weight of 36000;
(2) preparation of SPEEK modified CNTs, specifically: ultrasonically dispersing CNT and SPEEK in DMSO for 7min to prepare CNT/SPEEK suspension, centrifuging to collect solid components, and drying to water content of 0.48 wt% to obtain SPEEK modified CNT; wherein the CNT is multi-wall CNT modified by carboxyl, the concentration of the CNT in the CNT/SPEEK suspension is 0.06 wt%, and the concentration of the SPEEK in the CNT/SPEEK suspension is 2.5 wt%;
(3) mechanically blending the SPEEK modified CNT with PPS in a mass ratio of 2:100 by adopting a ball mill, then performing melt blending by twin-screw extrusion, and pressing to form a SPEEK @ CNT/PPS film with the thickness of 80 mu m; wherein the mechanical blending time is 15min, the melt blending temperature is 330 ℃, and the time is 10 min;
(4) preparing the SPEEK @ CNT/CF/PPS composite film by laminating and molding the SPEEK @ CNT/PPS film and the plain-woven CF two-dimensional fabric with the surface being de-sized; wherein, the method for desizing the surface of the CF two-dimensional fabric is to reflux the CF two-dimensional fabric for 2.5 hours by acetone at 50 ℃; the lamination molding is to place two SPEEK @ CNT/PPS films on two sides of a CF two-dimensional fabric with the surface thereof being de-sized respectively, lay the two films in a mold flatly and perform hot press molding; the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 3 min; the molding temperature is 330 ℃, and the molding pressure is 0.9 MPa; the molding time is 9min, and the cooling rate is 70 ℃/min;
(5) the SPEEK @ CNT/CF/PPS composite film is used as an implantation layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength; wherein, the CF is in the form of satin fabric, and the resin matrix of the CF reinforced thermoplastic composite material is PPS; the specific process of induction welding is as follows: firstly, cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust with acetone, and drying; then, the SPEEK @ CNT/CF/PPS composite film is placed between an upper welding sample strip and a lower welding sample strip, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, regulating the frequency of the current generator to be 25kHz, regulating the output power of a power supply to be 25kW, and after 1min of induction heating, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength.
The single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/PPS composite film implanted layer is 41MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 33 MPa.
Example 3
The induction welding method of the thermoplastic composite material with high welding strength and the implanted layer comprises the following specific steps:
(1) the SPEEK is prepared by the sulfonation reaction of PEEK and concentrated sulfuric acid, and specifically comprises the following steps: slowly adding dried PEEK powder into 98wt% concentrated sulfuric acid at 25 ℃ according to the proportion of 0.1g/ml, stirring until the powder is completely dissolved, heating the solution to 52 ℃, stirring for 3h, cooling to 25 ℃, slowly adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and drying to obtain SPEEK with the viscosity average molecular weight of 41000;
(2) preparation of SPEEK modified CNTs, specifically: ultrasonically dispersing CNT and SPEEK in DMF for 10min to prepare CNT/SPEEK suspension, centrifuging to collect solid components in the suspension, and drying to water content of 0.45 wt% to obtain SPEEK modified CNT; wherein the CNT is multi-wall CNT modified by carboxyl, the concentration of the CNT in the CNT/SPEEK suspension is 0.07 wt%, and the concentration of the SPEEK is 2 wt%;
(3) mechanically blending the SPEEK modified CNT with PPS in a mass ratio of 2.5:100 by adopting a ball mill, then performing melt blending by twin-screw extrusion, and pressing to form a SPEEK @ CNT/PPS film with the thickness of 100 mu m; wherein the mechanical blending time is 10min, the melt blending temperature is 350 ℃, and the time is 20 min;
(4) preparing the SPEEK @ CNT/CF/PPS composite film by laminating and molding the SPEEK @ CNT/PPS film and the plain-woven CF two-dimensional fabric with the surface being de-sized; wherein, the method for desizing the surface of the CF two-dimensional fabric is to reflux the CF two-dimensional fabric for 3 hours by acetone at 60 ℃; the lamination molding is to place two SPEEK @ CNT/PPS films on two sides of a CF two-dimensional fabric with the surface thereof being de-sized respectively, lay the two films in a mold flatly and perform hot press molding; the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 5 min; the molding temperature is 350 ℃, and the molding pressure is 1.2 MPa; the molding time is 8min, and the cooling rate is 20 ℃/min;
(5) the SPEEK @ CNT/CF/PPS composite film is used as an implantation layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength; wherein, the CF is twill fabric, and the resin matrix of the CF reinforced thermoplastic composite material is PPS; the specific process of induction welding is as follows: firstly, cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust with acetone, and drying; then, the SPEEK @ CNT/CF/PPS composite film is placed between an upper welding sample strip and a lower welding sample strip, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, regulating the frequency of the current generator to be 30kHz, regulating the output power of a power supply to be 30kW, and after 1.2min of induction heating, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength.
The single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/PPS composite film implanted layer is 45MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 37 MPa.
Example 4
The induction welding method of the thermoplastic composite material with high welding strength and the implanted layer comprises the following specific steps:
(1) the SPEEK is prepared by the sulfonation reaction of PEEK and concentrated sulfuric acid, and specifically comprises the following steps: slowly adding dried PEEK powder into 98wt% concentrated sulfuric acid at 26 ℃ according to the proportion of 0.2g/ml, stirring until the powder is completely dissolved, heating the solution to 53 ℃, stirring for 2h, cooling to 26 ℃, slowly adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and drying to obtain SPEEK with the viscosity average molecular weight of 51000;
(2) preparation of SPEEK modified CNTs, specifically: ultrasonically dispersing CNT and SPEEK in DMSO for 13min to prepare CNT/SPEEK suspension, centrifuging to collect solid components, and drying to water content of 0.3 wt% to obtain SPEEK modified CNT; wherein the CNT is multi-wall CNT modified by carboxyl, the concentration of the CNT in the CNT/SPEEK suspension is 0.1wt%, and the concentration of the SPEEK is 2.3 wt%;
(3) mechanically blending the SPEEK modified CNT with PEEK in a mass ratio of 3:100 by adopting a ball mill, then performing melt blending through twin-screw extrusion, and then pressing into a SPEEK @ CNT/PEEK film with the thickness of 115 mu m; wherein the mechanical blending time is 8min, the melt blending temperature is 370 ℃, and the time is 12 min;
(4) the SPEEK @ CNT/PEEK film and the twill CF two-dimensional fabric with the surface being de-sized are subjected to laminated molding to prepare the SPEEK @ CNT/CF/PEEK composite film; wherein, the method for desizing the surface of the CF two-dimensional fabric is to reflux the CF two-dimensional fabric for 3.5 hours by acetone at 70 ℃; the lamination molding is to respectively place two SPEEK @ CNT/PEEK films on two sides of a CF two-dimensional fabric with the surface thereof being de-sized, flatly lay the two films in a mold and carry out hot press molding; the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 6 min; the molding temperature is 370 ℃, and the molding pressure is 1.5 MPa; the molding time is 7min, and the cooling rate is 40 ℃/min;
(5) the SPEEK @ CNT/CF/PEEK composite film is used as an implantation layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength; wherein, the CF is in the form of a unidirectional tape, and the resin matrix of the CF reinforced thermoplastic composite material is PEEK; the specific process of induction welding is as follows: firstly, cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust with acetone, and drying; then, the SPEEK @ CNT/CF/PEEK composite film is placed between an upper welding sample strip and a lower welding sample strip, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, regulating the frequency of the current generator to be 35kHz, regulating the output power of a power supply to be 35kW, and after induction heating for 1.5min, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength.
The single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/PEEK composite film implantation layer is 49MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 38 MPa.
Example 5
The induction welding method of the thermoplastic composite material with high welding strength and the implanted layer comprises the following specific steps:
(1) the SPEEK is prepared by the sulfonation reaction of PEEK and concentrated sulfuric acid, and specifically comprises the following steps: slowly adding dried PEEK powder into 98wt% concentrated sulfuric acid at 27 ℃ according to the proportion of 0.3g/ml, stirring until the powder is completely dissolved, heating the solution to 55 ℃, stirring for 1h, cooling to 27 ℃, slowly adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and drying to obtain SPEEK with the viscosity average molecular weight of 60000;
(2) preparation of SPEEK modified CNTs, specifically: ultrasonically dispersing CNT and SPEEK in DMF for 20min to prepare CNT/SPEEK suspension, centrifuging to collect solid components in the suspension, and drying to water content of 0.2 wt% to obtain SPEEK modified CNT; wherein the CNT is multi-wall CNT modified by carboxyl, the concentration of the CNT in the CNT/SPEEK suspension is 0.08 wt%, and the concentration of the SPEEK is 1.7 wt%;
(3) mechanically blending the SPEEK modified CNT with PEEK in a mass ratio of 3.5:100 by using a ball mill, then performing melt blending by twin-screw extrusion, and then pressing into a SPEEK @ CNT/PEEK film with the thickness of 130 mu m; wherein the mechanical blending time is 12min, the melt blending temperature is 420 ℃, and the time is 15 min;
(4) the SPEEK @ CNT/PEEK film and the twill CF two-dimensional fabric with the surface being de-sized are subjected to laminated molding to prepare the SPEEK @ CNT/CF/PEEK composite film; wherein, the method for desizing the surface of the CF two-dimensional fabric is to reflux the CF two-dimensional fabric for 4 hours by acetone at 80 ℃; the lamination molding is to respectively place two SPEEK @ CNT/PEEK films on two sides of a CF two-dimensional fabric with the surface thereof being de-sized, flatly lay the two films in a mold and carry out hot press molding; the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 7 min; the molding temperature is 420 ℃, and the molding pressure is 1.7 MPa; the molding time is 6min, and the cooling rate is 50 ℃/min;
(5) the SPEEK @ CNT/CF/PEEK composite film is used as an implantation layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength; wherein, the CF is in the form of plain weave fabric, and the resin matrix of the CF reinforced thermoplastic composite material is PEEK; the specific process of induction welding is as follows: firstly, cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust with acetone, and drying; then, the SPEEK @ CNT/CF/PEEK composite film is placed between an upper welding sample strip and a lower welding sample strip, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, regulating the frequency of the current generator to be 40kHz, regulating the output power of a power supply to be 40kW, and after induction heating for 2min, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength.
The single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/PEEK composite film implantation layer is 47MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 36 MPa.
Example 6
The induction welding method of the thermoplastic composite material with high welding strength and the implanted layer comprises the following specific steps:
(1) the SPEEK is prepared by the sulfonation reaction of PEEK and concentrated sulfuric acid, and specifically comprises the following steps: slowly adding dried PEEK powder into 98wt% concentrated sulfuric acid at 25 ℃ according to the proportion of 0.15g/ml, stirring until the powder is completely dissolved, heating the solution to 53 ℃, stirring for 2h, cooling to 25 ℃, slowly adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and drying to obtain SPEEK with viscosity average molecular weight of 43000;
(2) preparation of SPEEK modified CNTs, specifically: ultrasonically dispersing CNT and SPEEK in DMSO for 18min to prepare CNT/SPEEK suspension, centrifuging to collect solid components, and drying to water content of 0.3 wt% to obtain SPEEK modified CNT; wherein the CNT is multi-wall CNT modified by carboxyl, the concentration of the CNT in the CNT/SPEEK suspension is 0.09 wt%, and the concentration of the SPEEK in the CNT/SPEEK suspension is 1.9 wt%;
(3) mechanically blending the SPEEK modified CNT with PEKK in a mass ratio of 4:100 by adopting a ball mill, then performing melt blending through twin-screw extrusion, and then pressing into a SPEEK @ CNT/PEKK film with the thickness of 140 mu m; wherein the mechanical blending time is 4min, the melt blending temperature is 350 ℃, and the time is 18 min;
(4) preparing the SPEEK @ CNT/CF/PEKK composite film by laminating and molding the SPEEK @ CNT/PEKK film and the satin CF two-dimensional fabric with the surface thereof being desized; wherein, the method for desizing the surface of the CF two-dimensional fabric is to reflux the CF two-dimensional fabric for 3.5 hours by acetone at 70 ℃; the lamination mould pressing means that two SPEEK @ CNT/PEKK films are respectively placed on two sides of a CF two-dimensional fabric with the surface being de-sized, and the two films are flatly laid in a mould for hot press forming; the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 8 min; the molding temperature is 350 ℃, and the molding pressure is 2 MPa; the molding time is 5min, and the cooling rate is 60 ℃/min;
(5) the SPEEK @ CNT/CF/PEKK composite film is used as an implantation layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength; wherein, the CF is in the form of satin fabric, and the resin matrix of the CF reinforced thermoplastic composite material is PEKK; the specific process of induction welding is as follows: firstly, cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust with acetone, and drying; then, the SPEEK @ CNT/CF/PEKK composite film is placed between an upper welding spline and a lower welding spline, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, regulating the frequency of the current generator to be 37kHz, regulating the output power of a power supply to be 36kW, and after induction heating for 1.7min, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength.
The single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/PEKK composite film implantation layer is 48MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 39 MPa.
Example 7
The induction welding method of the thermoplastic composite material with high welding strength and the implanted layer comprises the following specific steps:
(1) the SPEEK is prepared by the sulfonation reaction of PEEK and concentrated sulfuric acid, and specifically comprises the following steps: slowly adding dried PEEK powder into 98wt% concentrated sulfuric acid at 24 ℃ according to the proportion of 0.25g/ml, stirring until the powder is completely dissolved, heating the solution to 54 ℃, stirring for 3h, cooling to 24 ℃, slowly adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and drying to obtain SPEEK with the viscosity average molecular weight of 51000;
(2) preparation of SPEEK modified CNTs, specifically: ultrasonically dispersing CNT and SPEEK in DMF for 16min to prepare CNT/SPEEK suspension, centrifuging to collect solid components in the suspension, and drying to water content of 0.4 wt% to obtain SPEEK modified CNT; wherein the CNT is multi-wall CNT modified by carboxyl, the concentration of the CNT in the CNT/SPEEK suspension is 0.06 wt%, and the concentration of the SPEEK is 2.1 wt%;
(3) mechanically blending the SPEEK modified CNT with PEKK in a mass ratio of 5:100 by adopting a ball mill, then performing melt blending by twin-screw extrusion, and then pressing into a SPEEK @ CNT/PEKK film with the thickness of 160 mu m; wherein the mechanical blending time is 6min, the melt blending temperature is 400 ℃, and the time is 17 min;
(4) preparing the SPEEK @ CNT/CF/PEKK composite film by laminating and molding the SPEEK @ CNT/PEKK film and the satin CF two-dimensional fabric with the surface thereof being desized; wherein, the method for desizing the surface of the CF two-dimensional fabric is to reflux the CF two-dimensional fabric for 3 hours by acetone at 60 ℃; the lamination mould pressing means that two SPEEK @ CNT/PEKK films are respectively placed on two sides of a CF two-dimensional fabric with the surface being de-sized, and the two films are flatly laid in a mould for hot press forming; the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 4 min; the molding temperature is 400 ℃, and the molding pressure is 1.6 MPa; the molding time is 7min, and the cooling rate is 30 ℃/min;
(5) the SPEEK @ CNT/CF/PEKK composite film is used as an implantation layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength; wherein, the CF is twill fabric, and the resin matrix of the CF reinforced thermoplastic composite material is PEKK; the specific process of induction welding is as follows: firstly, cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust with acetone, and drying; then, the SPEEK @ CNT/CF/PEKK composite film is placed between an upper welding spline and a lower welding spline, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, adjusting the frequency of the current generator to be 26kHz, adjusting the output power of a power supply to be 25kW, and after induction heating for 1.4min, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength.
The single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/PEKK composite film implantation layer is 43MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 34 MPa.
Claims (7)
1. The induction welding method of the thermoplastic composite material containing the implanted layer with high welding strength is characterized in that: the SPEEK @ CNT/CF/thermoplastic resin composite film is used as an implantation layer, and the CF reinforced thermoplastic composite material is subjected to induction welding to obtain a thermoplastic composite material connecting piece with high welding strength;
the preparation method of the SPEEK @ CNT/CF/thermoplastic resin composite film comprises the following steps: firstly blending SPEEK modified CNT and a thermoplastic resin matrix and pressing the mixture into a SPEEK @ CNT/thermoplastic resin film, and then preparing the SPEEK @ CNT/thermoplastic resin film and a CF two-dimensional fabric with desized surface through laminating and mould pressing to obtain the SPEEK @ CNT/CF/thermoplastic resin composite film;
the SPEEK is prepared by a sulfonation reaction of PEEK and concentrated sulfuric acid, and the preparation method comprises the following specific steps: adding dried PEEK powder into 98wt% concentrated sulfuric acid at room temperature according to the proportion of 0.01-0.3 g/ml, stirring until the powder is completely dissolved, heating the solution to 50-55 ℃, stirring for 1-5 h, cooling to room temperature, adding the cooled solution into excessive ice water under stirring, separating out a precipitate, washing the precipitate with deionized water until the pH value is 7, and drying to obtain a product SPEEK;
the preparation steps of the SPEEK modified CNT are: ultrasonically dispersing CNT and SPEEK in a solvent for 5-20 min to prepare a CNT/SPEEK suspension, centrifugally collecting solid components in the suspension, and drying until the water content is less than 0.5wt%, so as to obtain the SPEEK modified CNT;
CNT is carboxyl modified multi-wall CNT, viscosity average molecular weight of SPEEK is 30000-60000, solvent of CNT/SPEEK suspension is DMF or DMSO, concentration of CNT in CNT/SPEEK suspension is 0.05-0.1 wt%, concentration of SPEEK is 1.5-2.5 wt%;
the single lap shear strength of the thermoplastic composite material connecting piece based on the SPEEK @ CNT/CF/thermoplastic resin composite film implantation layer is 38-49 MPa, and the single lap shear strength of the connecting piece after 30 ten thousand shear direction tensile fatigue tests is 30-39 MPa.
2. The induction welding method of claim 1, wherein the resin matrix of the CF reinforced thermoplastic composite is PPS, PEEK or PEKK, and the CF in the CF reinforced thermoplastic composite is in the form of plain weave, satin weave, twill weave or unidirectional tape.
3. The induction welding method of thermoplastic composite implant-containing layer with high welding strength as set forth in claim 2, wherein the resin matrix in the SPEEK @ CNT/CF/thermoplastic resin composite film is the same as the resin matrix to be welded with the CF reinforced thermoplastic composite.
4. The induction welding method of claim 1, wherein the SPEEK modified CNT is blended with the thermoplastic resin matrix by mechanically blending with a ball mill and melt blending with twin screw extrusion; the SPEEK @ CNT/thermoplastic resin film has a thickness of 60 to 160 μm.
5. The induction welding method of thermoplastic composite implant-containing layer with high welding strength as claimed in claim 1, wherein the CF two-dimensional fabric is in the form of plain, satin or twill;
the method for desizing the surface of the CF two-dimensional fabric comprises the steps of refluxing the CF two-dimensional fabric with acetone for 2-4 hours at the temperature of 40-80 ℃;
the lamination molding is to place two SPEEK @ CNT/thermoplastic resin films on two sides of a CF two-dimensional fabric with the surface thereof being de-sized respectively, lay the two-dimensional fabric in a mold flatly and perform hot press molding.
6. The induction welding method for the thermoplastic composite material with high welding strength and the implanted layer according to claim 5, characterized in that the hot press forming comprises three stages of preheating, forming and cooling, and the technological parameters of each stage are as follows: preheating for 2-8 min, wherein the molding pressure is 0.5-2 MPa, the molding temperature is T1-T2, the molding time is 5-10 min, and the cooling rate is 1-70 ℃/min;
when the resin film is made of PPS, T1 is 310 ℃, and T2 is 350 ℃;
when the resin film is made of PEEK, the T1 is 370 ℃, and the T2 is 420 ℃;
when the resin film is PEKK, T1 is 350 ℃ and T2 is 400 ℃.
7. The method for induction welding of the implant-containing layer of the thermoplastic composite material with high welding strength as claimed in claim 1, wherein the specific process of the induction welding is as follows: firstly, cutting the CF reinforced thermoplastic composite material laminated plate into welding sample strips according to an ASTM D5868 lap shear test standard, wiping surface dust with acetone, and drying; then, the SPEEK @ CNT/CF/thermoplastic resin composite film is placed between an upper welding sample strip and a lower welding sample strip, and the three parts of materials are integrally placed below the induction coil; a vacuum bag is arranged outside the whole body and is vacuumized, so that the whole body is compacted by atmospheric pressure in the fusion welding process; and (3) switching on the current in the induction coil, adjusting the frequency of the current generator to be 20-40 kHz, adjusting the output power of the power supply to be 20-40 kW, and after induction heating for 0.8-2 min, maintaining the pressure and naturally cooling to obtain the thermoplastic composite material connecting piece with high welding strength.
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Application publication date: 20210629 Assignee: Suzhou Sky Composite Technology Co.,Ltd. Assignor: DONGHUA University Contract record no.: X2024980002403 Denomination of invention: Induction welding method for thermoplastic composite materials with high welding strength containing implanted layers Granted publication date: 20220208 License type: Common License Record date: 20240304 |