Background
The coated hard alloy is generally formed by coating a super-hard material layer on a hard alloy substrate, so that the advantages of good toughness, strength and impact resistance of the hard alloy substrate, high wear resistance, high hardness, excellent high-temperature oxidation resistance and the like of the super-hard material layer are integrated. At present, the development of the coating hard alloy is changing day by day, the grade of the coating hard alloy is more endless, and the report research on the influence of Co on the coating in the coating process, the coating structure and components, the hard alloy matrix and the like is very abundant. While the coating process and performance are continuously optimized, more rigorous requirements are put forward on the hard alloy matrix. This is because the properties of the coated cemented carbide depend to a large extent on the matching properties of the coating to the cemented carbide substrate.
In order to improve the matching properties with diamond coatings, cemented carbides should have the following 3 requirements: 1) has enough rigidity, and can not be strained too much when being subjected to load or impact, otherwise the peeling of the coating is easily caused; 2) the thermal expansion coefficient of the substrate is similar to that of the corresponding coating material, otherwise, the thermal stress generated in the operation process is too large, so that the coating is cracked or fails; 3) the material composition of the cemented carbide substrate or the substrate surface layer is compatible with the composition of the corresponding coating material, otherwise the growth of the coating material is not facilitated, especially for the nucleation and growth of the diamond coating. The requirement 1) is easy to meet with enough rigidity, and even the common hard alloy can better meet the requirement by reducing the Co content and refining WC crystal grains; for the requirement 2) close thermal expansion coefficient, the review shows that the stress is higher for the traditional WC-Co hard alloy, and the double-layer structure multi-element gradient hard alloy has potential advantages; for requirement 3), conventional WC-Co cemented carbides are mainly WC, Co and possibly a third phase (free C or η phase), and thus it is difficult to achieve composition adjustments to form a matrix that matches the coating.
CVD diamond coating has been developed over 20 years, mainly in solving 3 key technical difficulties: 1) the quality of the CVD diamond film on the hard alloy substrate is ensured; 2) Is the nucleation and growth of diamond film; 3) is the bonding strength between the diamond film and the cemented carbide substrate. For the technical difficulty 1), the nano diamond film with excellent performance can be prepared at present; for the technical difficulty 2), the binding phase of the traditional WC-Co hard alloy is mainly Co, and in the process of depositing diamond, the C element has better solubility and higher diffusion coefficient in Co, so that the nucleation of a diamond film is very unfavorable; for the technical difficulty 3), a transition layer with specific performance is mainly prepared by PVD or CVD equipment and the like so as to relieve the difference of the thermal expansion coefficients between the hard alloy and the diamond film. Through depositing the transition layer on the substrate and then preparing the microwave diamond film, although the problems of nucleation and growth of the diamond film and the bonding strength between the diamond film and the hard alloy substrate can be solved, the additional process flow is increased, the production application is not facilitated, and the cost is reduced.
Improving the bonding strength of the diamond film and the cutter substrate is one of the current research focuses, such as the preparation method of the cutter disclosed in patent document CN201610716152.0 and the preparation method of the composite diamond film coating on the surface of the hard alloy cutter disclosed in patent document 201810849326. X. The preparation method of the cutter disclosed in patent document CN201610716152.0 includes: (1) pretreating the hard alloy matrix to coarsen the surface of the hard alloy matrix and reduce the content of cobalt element on the surface of the matrix; the pretreatment method comprises the following steps: etching the WC phase in a first reagent in a manner of ultrasonic vibration for 20-40 minutes, wherein the first reagent is a mixed solution of K3(Fe (CN))6 and KOH; the second reagent is sulfuric acid solution, and the first reagent contains K3(Fe (CN)) 6: KOH: H2O in a mass ratio of 1: 1-1.5: 6-8; and (3) carrying out acid etching on the etched hard alloy substrate in a second reagent for 8-10 seconds, wherein the volume ratio of H2SO4 to H2O2 in the second reagent is 3 to (5-7). (2) Carrying out microwave decarburization reduction treatment on the hard alloy matrix to convert WC on the surface of the matrix into W; the reduction treatment time is 10-15 minutes; the microwave power is 400-550W, and the gas pressure is 1-1.5 kPa. (3) Placing the hard alloy substrate into a bias enhanced hot wire device to deposit the diamond film coating, wherein the deposition time is 1-1.5 hours, the temperature of the hot wire is 800-1000 ℃, and the bias current density is 0.1-0.15A/cm 2; forming a diamond film on the surface of the hard alloy substrate.
The patent document 201810849326.X discloses a preparation method of a composite diamond film coating on the surface of a hard alloy cutter, which comprises the following steps: (1) and polishing the hard alloy cutter by using sand paper, then placing the hard alloy cutter in an acidic solution A for ultrasonic treatment for 10-12min, then placing the hard alloy cutter in an alkaline solution B for ultrasonic treatment for 6-8min, cleaning the hard alloy cutter by using acetone, placing the cleaned hard alloy cutter in a diamond micropowder acetone suspension for ultrasonic oscillation for 15-18min, and cleaning and drying the hard alloy cutter to obtain the pretreated hard alloy cutter. The acid solution A is composed of potassium permanganate solution and hydrogen peroxide according to the volume ratio of 1.5-3: 1, the alkaline solution B is composed of sodium hydroxide aqueous solution with the concentration of 18-25 wt% and calcium hydroxide aqueous solution with the concentration of 2-5 wt% according to the volume ratio of 3-5: 1, and the diamond micro powder in the diamond micro powder acetone suspension is composed of two parts with the granularity of 4 mu m and the granularity of 8 mu m according to the weight ratio of 2-4: 1-1.5; and obtaining the pretreated hard alloy cutter. (2) Carrying out hot wire chemical vapor deposition treatment on the surface of the pretreated hard alloy cutter to obtain a material A; the hot wire chemical vapor deposition parameters were as follows: the temperature of the hot wire is 2300-2350 ℃, the temperature of the substrate is 730-760 ℃, the swinging angle of the substrate is 90-180 ℃, the swinging is 3-4 times per minute, the distance between the hot wire and the substrate is 6.5-8mm, the flow rate of methane is 10-12sccm, the flow rate of hydrogen is 600-700sccm, the flow rate of argon is 200-220sccm, the working pressure in the reaction chamber is 150-200KPa, and the deposition time is 35-40 min. (3) Placing the material A in acetone, ultrasonically washing, drying at 80-90 ℃, then soaking in AlO sol for 1-2min, taking out, drying at 60-65 ℃ for 3-5min, and then soaking in SiO sol for 1-2 min; taking out and then carrying out heat treatment, wherein the heat treatment comprises the following specific processes: heating the material to 90-95 ℃ at a speed of 1-2 ℃/min, preserving heat for 35-45min, heating to 720-; and obtaining the composite diamond film coating on the surface of the hard alloy cutter. According to the invention, by optimizing the pretreatment process of the hard alloy cutter and reasonably selecting reagents and process parameters, impurities on the surface of the hard alloy cutter are effectively removed, the activity of the hard alloy cutter is improved, and metal particles on the surface of the hard alloy cutter are refined, so that the subsequent generation of a composite diamond film coating is facilitated; and then by optimizing the hot wire chemical vapor deposition process, the process parameters are reasonably set, the surface of the substrate can uniformly accept the radiation of the hot wire, the uniformity of the temperature field on the surface of the substrate is improved, the change condition of multipoint temperature on the surface of the substrate can be continuously detected, the uniformity and the stability of the diamond film are effectively improved, diamond is deposited on the surface of the hard alloy cutter, the nucleation density is high, the growth of crystal grains is effectively inhibited through secondary nucleation, the micron/nano diamond composite film is formed, the micron/nano diamond composite film has excellent adhesion strength on the surface of the matrix of the hard alloy cutter, is not easy to peel off, and the cutting performance, the high temperature resistance and other performances of the cutter are obviously improved.
Disclosure of Invention
The invention provides a method for preparing a diamond coating gradient hard alloy cutter by directly combining a nitriding sintered substrate and a microwave coating, aiming at the problem that a transition layer needs to be deposited on the substrate before a microwave diamond film is manufactured on the hard alloy substrate, otherwise a graphite layer is formed on the surface.
In order to achieve the purpose, the invention adopts the following technical scheme.
A method for preparing a diamond coating gradient hard alloy cutter directly combined by a nitriding sintered substrate and a microwave coating comprises the following steps:
s1 preparation of composite powder: ball-milling the mixed powder in H2 atmosphere for more than 24H, heating the ball-milled mixed powder to 990-1050 ℃ and preserving the heat for 110-130min to obtain composite powder; the mixed powder comprises the following components in percentage by mass: 25-40% TiO20.5-1.5% of VC and 0.5-1.5% of Cr3C21-2% of Mo, 3-6% of Co, 3-6% of Ni and 43-67% of carbon-tungsten mixed powder; the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
Preferably, in step S1, the mixed powder and the cemented carbide balls are filled into a cemented carbide ball mill pot with a ball-to-material ratio of 20:1 in H2Ball milling is carried out in the atmosphere.
More preferably, before ball milling, the cemented carbide ball milling jar filled with the mixed powder and the cemented carbide balls is vacuumized to 10 degrees-1pa followed by H2Repeating the vacuumizing and H2 introducing for 3 times; during ball milling, the hard alloy ball milling tank is cooled by water.
Preferably, in step S1, the ball-milled mixed powder is heated to 1000 ℃ and kept at the temperature for 120 min.
Preferably, the mixed powder consists of the following components in percentage by mass: 25-30% of TiO20.5-1.5% of VC and 0.5-1.5% of Cr3C21-2% of Mo, 3-6% of Co, 3-6% of Ni and 60-67% of carbon-tungsten mixed powder; the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
S2 preparation of the matrix: pressing the composite powder into a green body, and sequentially performing first-step sintering and second-step sintering on the green body to obtain a matrix; the first step of sintering is heating the green body to 900 ℃ in vacuum atmosphere and preserving heat for 25-35min, and the second step of sintering is heating the green body to 1450 ℃ and preserving heat for 55-65min under the protection of 0.1-10MPa nitrogen; in the first step of sintering, the temperature rise rate in the region of 390-410 ℃ is 0.3-0.4 ℃/min.
Preferably, in the first-step sintering, the temperature rise rate in the interval of 390-410 ℃ is 0.33 ℃/min;
preferably, in the first-step sintering, the temperature is raised to 390 ℃ at the speed of 5 ℃/min, then the temperature is raised to 410 ℃ at the speed of 0.33 ℃/min, and then the temperature is raised to 900 ℃ at the speed of 5 ℃/min; in the second sintering step, the temperature is raised to 1450 ℃ at the speed of 5 ℃/min.
More preferably, in the first sintering step, the green body is heated to 900 ℃ and kept for 30 min.
More preferably, in the second sintering step, the green body is heated to 1450 ℃ and is kept at the temperature for 60 min.
More preferably, the green body is placed in a graphite boat and embedded in alumina before sintering.
The blank is a cuboid with the length of 18.0mm, the width of 18.0mm and the height of 9.0 mm.
S3 preparing diamond coating: after cleaning the substrate, a diamond coating is deposited on the substrate by microwave plasma chemical vapor deposition.
Preferably, in step S3, the cleaned substrate is placed in a microwave plasma cvd apparatus, and H is introduced into the apparatus under vacuum2Until the pressure in the reaction chamber is 1kPa, then CH is introduced4Gas, hold CH4Concentration of 1.5%, gas flow of 600sccm, deposition pressure17kPa, microwave power of 6kw, deposition temperature of 900 ℃ and deposition time of 8 h.
Compared with the prior art, the invention has the beneficial effects that:
the invention can realize the generation of nano (Ti, W) C-Ni-Co-V-Cr-Mo composite powder by adjusting the composition of the composite powder and combining high-energy ball milling with high-temperature reaction, wherein the reaction temperature is controlled to be about 1000 ℃; when the composite powder is used for sintering the matrix, the matrix on which the CVD diamond coating can be directly manufactured can be obtained by sintering through two-step sintering of vacuum and nitriding and controlling the temperature rise rate of the vacuum sintering in the range of 390-410 ℃, a transition layer is manufactured without preprocessing the matrix, and the bonding property of the coating and the matrix is good.
Detailed Description
In order to more fully understand the technical contents of the present invention, the technical solutions of the present invention will be further described and illustrated with reference to the following specific embodiments.
The features, benefits and advantages of the present invention will become apparent to those skilled in the art from a reading of the present disclosure. The raw materials used in the examples are all commercially available products.
Example 1
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter. The method comprises the following specific steps:
(1) preparation of composite powder
Preparing materials: weighing the powder materials according to the following mass percentages, wherein the total weight is 100%: 27% TiO2VC 1%, Cr 1%3C21% of Mo, 4% of Co, 4% of Ni and the balance of carbon-tungsten mixed powder, wherein the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
High-energy ball milling:putting the powder and the hard alloy balls into a hard alloy ball milling tank, wherein the ball-material ratio is 20: 1; before ball milling, a hard alloy ball milling tank filled with mixed powder and hard alloy balls is vacuumized to 10 DEG-1pa followed by H2Repeating the vacuum-pumping and H-pumping for 3 times2(ii) a And then ball-milling for more than 24H in an H2 atmosphere. During ball milling, the hard alloy ball milling tank is cooled by water.
High-temperature reaction: and heating the ball-milled powder to 1000 ℃ and preserving the heat for 120min to obtain the composite powder.
(2) Preparation of the substrate
The composite powder is pressed into a cuboid blank with the length of 18.0mm, the width of 18.0mm and the height of 9.0 mm. And (3) placing the blank in a graphite boat and embedding the blank by using aluminum oxide, and then sequentially carrying out the first-step sintering and the second-step sintering on the blank to obtain the matrix.
Sintering in the first step: heating to 390 deg.C at 5 deg.C/min in vacuum atmosphere, controlling the heating rate at 0.3-0.4 deg.C/min, preferably at 0.33 deg.C/min, heating to 410 deg.C at this rate, heating to 900 deg.C at 5 deg.C/min, and holding for 30 min.
And a second step of sintering: heating to 1450 deg.C at a rate of 5 deg.C/min, and maintaining under nitrogen protection of 0.1-10MPa for 60 min.
(3) Preparation of Diamond coatings
And placing the cooled substrate in acetone for ultrasonic cleaning for more than 5min, then placing the substrate in ethanol for ultrasonic cleaning for more than 5min to clean the surface of the substrate, and then drying the substrate for coating experiments.
Putting the substrate into microwave plasma chemical vapor deposition equipment, and manufacturing a coating on the substrate by adopting a conventional microwave plasma chemical vapor deposition method, wherein the method specifically comprises the following steps: firstly introducing H under the vacuum condition2Until the pressure in the reaction chamber is 1kPa, then CH is introduced4Gas, hold CH4The concentration of the silicon dioxide is 1.5 percent, the gas flow is 600sccm, the deposition pressure is 17kPa, the microwave power is 6kw, the deposition temperature is 900 ℃, and the deposition time is 8 hours.
Example 2
The embodiment provides a diamond coating gradient hard alloyThe preparation method of the cutter comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; the steps (2) and (3) are the same as those in the embodiment 1, and the step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the high-energy ball milling and the high-temperature reaction are the same as those in the embodiment 1, and only the material preparation is different from that in the embodiment 1, specifically, the powder materials are respectively weighed according to the following mass percentages, and the total amount is 100%: 30% TiO2VC 1%, Cr 1%3C21% of Mo, 3% of Co, 3% of Ni and the balance of carbon-tungsten mixed powder, wherein the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
Example 3
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; the steps (2) and (3) are the same as those in the embodiment 1, and the step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the high-energy ball milling and the high-temperature reaction are the same as those in the embodiment 1, and only the material preparation is different from that in the embodiment 1, specifically, the powder materials are respectively weighed according to the following mass percentages, and the total amount is 100%: 32% TiO20.5% of VC and 0.5% of Cr3C21% of Mo, 3% of Co, 3% of Ni and the balance of carbon-tungsten mixed powder, wherein the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
Example 4
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; the steps (2) and (3) are the same as those in the embodiment 1, and the step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the high-energy ball milling and the high-temperature reaction are the same as those in the embodiment 1, and only the material preparation is different from that in the embodiment 1, specifically, the powder materials are respectively weighed according to the following mass percentages, and the total amount is 100%: 40% TiO20.5% of VC and 0.5% of Cr3C21% of Mo, 3% of Co, 3% of Ni and the balance of carbon-tungsten mixed powder, wherein the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
Example 5
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; the steps (2) and (3) are the same as those in the embodiment 1, and the step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the high-energy ball milling and the high-temperature reaction are the same as those in the embodiment 1, and only the material preparation is different from that in the embodiment 1, specifically, the powder materials are respectively weighed according to the following mass percentages, and the total amount is 100%: 40% TiO21.5% of VC and 1.5% of Cr3C22% of Mo, 6% of Co, 6% of Ni and the balance of carbon-tungsten mixed powder, wherein the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
Example 6
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; the steps (2) and (3) are the same as those in the embodiment 1, and the step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the high-energy ball milling and the high-temperature reaction are the same as those in the embodiment 1, and only the material preparation is different from that in the embodiment 1, specifically, the powder materials are respectively weighed according to the following mass percentages, and the total amount is 100%: 27% TiO2VC 1%, Cr 1%3C21% of Mo, 4% of Co, 4% of Ni and the balance of carbon-tungsten mixed powder, wherein the carbon-tungsten mixed powder consists of 10% of C and 90% of W.
Example 7
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; the steps (2) and (3) are the same as those in the embodiment 1, and the step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the high-energy ball milling and the high-temperature reaction are the same as those in the embodiment 1, and only the material preparation is different from that in the embodiment 1, specifically, the powder materials are respectively weighed according to the following mass percentages, and the total amount is 100%: 20% of TiO2VC 1%, Cr 1%3C21% of Mo, 4% of Co, 4% of Ni and 69% of carbon-tungsten mixtureMixing the powder, wherein the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
Example 8
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; the steps (2) and (3) are the same as those in the embodiment 1, and the step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the high-energy ball milling and the high-temperature reaction are the same as those in the embodiment 1, and only the material preparation is different from that in the embodiment 1, specifically, the powder materials are respectively weighed according to the following mass percentages, and the total amount is 100%: 30% TiO21% of Mo, 4% of Co, 4% of Ni and the balance of carbon-tungsten mixed powder, wherein the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
Example 9
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; the steps (2) and (3) are the same as those in the embodiment 1, and the step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the high-energy ball milling and the high-temperature reaction are the same as those in the embodiment 1, and only the material preparation is different from that in the embodiment 1, specifically, the powder materials are respectively weighed according to the following mass percentages, and the total amount is 100%: 28% TiO2VC 1%, Cr 1%3C24% of Co, 4% of Ni and the balance of carbon-tungsten mixed powder, wherein the carbon-tungsten mixed powder consists of 6% of C and 94% of W.
Example 10
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; steps (2) and (3) are the same as those of embodiment 1, and step (1) comprises material preparation, ball milling and high-temperature reaction, wherein the material preparation and the high-temperature reaction are the same as those of embodiment 1, and are different from those of embodiment 1 in ball milling, and specifically, the steps of: and (3) putting the powder and the hard alloy balls into a hard alloy ball milling tank, wherein the ball-material ratio is 10: 1, and ball milling is carried out for more than 24 hours. During ball milling, the hard alloy ball milling tank is cooled by water.
Example 11
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; steps (2) and (3) are the same as in example 1, and step (1) comprises material preparation, ball milling and high temperature reaction, wherein the material preparation is the same as in example 1, and the ball milling and high temperature reaction are different from that in example 1, and the details are as follows.
Ball milling: and (3) putting the powder and the hard alloy balls into a hard alloy ball milling tank, wherein the ball-material ratio is 10: 1, and ball milling is carried out for more than 24 hours. During ball milling, the hard alloy ball milling tank is cooled by water.
High-temperature reaction: and heating the ball-milled powder to 1100 ℃ and preserving the temperature for 120min to obtain the composite powder.
Example 12
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; steps (2) and (3) are the same as those of embodiment 1, and step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the material preparation and the high-energy ball milling are the same as those of embodiment 1, and the high-temperature reaction is different from that of embodiment 1, and specifically: and heating the ball-milled powder to 1100 ℃ and preserving the temperature for 120min to obtain the composite powder.
Example 13
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; steps (2) and (3) are the same as those of embodiment 1, and step (1) comprises material preparation, high-energy ball milling and high-temperature reaction, wherein the material preparation and the high-energy ball milling are the same as those of embodiment 1, and the high-temperature reaction is different from that of embodiment 1, and specifically: and heating the ball-milled powder to 900 ℃ and preserving the heat for 120min to obtain the composite powder.
Example 14
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; steps (1) and (3) were the same as in example 1, and step (2) was as follows.
A green body having the same size as in example 1 was prepared, and then the first-step sintering and the second-step sintering were sequentially performed on the green body to obtain a base.
Sintering in the first step: heating to 900 ℃ at the speed of 5 ℃/min in vacuum atmosphere and preserving heat for 30 min.
And a second step of sintering: heating to 1450 deg.C at a rate of 5 deg.C/min, and maintaining under nitrogen protection of 0.1-10MPa for 60 min.
Example 15
The embodiment provides a preparation method of a diamond coating gradient hard alloy cutter, which comprises the steps of (1) preparing composite powder, (2) preparing a substrate and (3) preparing a diamond coating; steps (1) and (3) were the same as in example 1, and step (2) was as follows.
A green body having the same size as in example 1 was prepared, and then the first-step sintering and the second-step sintering were sequentially performed on the green body to obtain a base.
Sintering in the first step: in vacuum atmosphere, heating to 400 deg.C at 5 deg.C/min, heating to 500 deg.C at 2 deg.C/min, heating to 900 deg.C at 5 deg.C/min, and holding for 30 min.
And a second step of sintering: heating to 1450 deg.C at a rate of 5 deg.C/min, and maintaining under nitrogen protection of 0.1-10MPa for 60 min.
For the diamond coating gradient cemented carbide tools prepared in the above examples 1 to 15, SEM was used to study the surface topography of the diamond coating; and the following mechanical property tests were carried out: measuring the nano hardness value and the elastic modulus of the diamond coating by adopting nano indentation of an in-situ nano mechanical testing system, wherein the loading load is 5000 mu N, the loading time is 5s, obtaining an experimental value according to a measured loading and unloading curve, repeating the experiment for three times, and then taking an average value; and measuring the change of the surface friction coefficient of the diamond coating by using a friction and wear tester. The test results are summarized in the following table, and it can be seen from the test results that examples 1 to 5 pass
The composition of the composite powder is adjusted, high-energy ball milling and high-temperature reaction are combined, and the reaction temperature is controlled to be about 1000 ℃ to generate nano (Ti, W) C-Ni-Co-V-Cr-Mo composite powder; when the matrix is sintered, the matrix on which the CVD diamond coating can be directly manufactured can be obtained by sintering through two-step sintering of vacuum and nitriding and controlling the temperature rise rate of the vacuum sintering within the range of 390-410 ℃, a transition layer is manufactured without preprocessing the matrix, the bonding property of the coating and the matrix is good, and the manufactured cutter has excellent comprehensive performance in nano hardness, elastic modulus and friction coefficient.
Test object
|
Nanometer hardness (GPa)
|
Modulus of elasticity (GPa)
|
Coefficient of friction
|
Example 1
|
37.8
|
326
|
0.12
|
Example 2
|
36.5
|
352
|
0.11
|
Example 3
|
38.6
|
375
|
0.11
|
Example 4
|
37.9
|
343
|
0.13
|
Example 5
|
38.8
|
365
|
0.11
|
Example 6
|
27.3
|
276
|
0.43
|
Example 7
|
28.2
|
253
|
0.47
|
Example 8
|
27.5
|
246
|
0.53
|
Example 9
|
26.1
|
276
|
0.46
|
Example 10
|
32.9
|
296
|
0.13
|
Example 11
|
30.5
|
266
|
0.23
|
Example 12
|
33.9
|
316
|
0.26
|
Example 13
|
31.3
|
273
|
0.28
|
Example 14
|
32.9
|
256
|
0.21
|
Example 15
|
32.4
|
269
|
0.27 |
The invention can realize the generation of nano (Ti, W) C-Ni-Co-V-Cr-Mo composite powder by adjusting the composition of the composite powder and combining high-energy ball milling with high-temperature reaction, wherein the reaction temperature is controlled to be about 1000 ℃; when the composite powder is used for sintering a substrate, the two-step sintering is carried out through vacuum and nitriding, and the temperature rise rate of the vacuum sintering in the range of 390-410 ℃ is controlled, so that the diamond coating is directly generated on the obtained substrate by using a microwave coating technology, and the quality of the diamond coating is very good. The diamond coating gradient hard alloy cutter manufactured by the method does not need to pretreat the substrate to form a transition layer to solve the problems of nucleation and growth of the diamond film and the bonding strength between the diamond film and the hard alloy substrate.
The technical contents of the present invention are further illustrated by the examples, so as to facilitate the understanding of the reader, but the embodiments of the present invention are not limited thereto, and any technical extension or re-creation based on the present invention is protected by the present invention.