The carbon material heater is used and the preparation method
Technical field
The present invention relates to a kind of high temperature field heater, specifically a kind of carbon material heater and preparation method, particularly relating to a kind of is the heater and the preparation method of matrix by carbon/carbon compound material or graphite material.
Background technology
A series of excellent characteristics such as carbon/carbon compound material or graphite material have good heat resistance, thermal-shock resistance is good, thermal conductivity is high, thermal coefficient of expansion is low, easy processing, high-temperature machinery intensity height, it is the optimal candidate material of preparation heater, but because there are a fatal shortcoming in carbon/carbon compound material or graphite, high temperature is very easily oxidized.Therefore, the heater of carbon/carbon compound material or graphite material preparation can only or have under the protective atmosphere condition in vacuum and uses.Yet, in actual production, require heater in air or under the aerobic environment, to use sometimes, this just requires heater itself to have oxidation resistance.
Zone-refine is the important method of preparation semi-conducting material and other high-purity material (metal, inorganic compound and organic compound).As when preparing monocrystalline germanium, need purify to the germanium raw material, its method of purification mainly is a zone-refine, being about to germanium ingot (by high-purity germanium dioxide reduction) places in the high purity graphite boat, graphite boat places quartz ampoule, outside quartz ampoule, load radio-frequency induction coil, radio-frequency induction coil places an end of germanium ingot, the induced current that produces by high-frequency induction magnetic field heats graphite boat, thereby heating germanium ingot, rising along with temperature, self also becomes conductor the germanium ingot, cause the germanium ingot to be higher than other position in the temperature of radio-frequency induction coil one end, when temperature is higher than the fusing point of germanium, can produce local melting zone in this zone, move quartz ampoule with certain speed then, make the melting zone move to the other end from an end, in mobile melting zone, the germanium of fusing also solidifies gradually earlier, because solid solution is selectable crystallization, the germanium crystal of elder generation's crystallization enters solute (impurity) in the germanium melt of melt portions, so after the melting range was walked to go over, the impurity in the germanium ingot will be enriched in the other end, repeats can reach several times the purpose of purifying germanium ingot, at last enrichment impurity end is removed get final product high-purity polycrystalline germanium, by Czochralski method etc. polycrystalline germanium is drawn into monocrystalline germanium then.
Above-mentioned method is suitable for preparing the germanium single crystal that purity is 6N, but in actual applications, sometimes needing purity is the germanium single crystal of 9N even 12N, this has higher purity with regard to requiring the polycrystalline germanium after the zone-refine, but because the pollution of graphite boat, be difficult to prepare the polycrystalline germanium of purity greater than 9N even 12N, therefore, in actual production, generally being to be that the polycrystalline germanium of 6N is a raw material with purity, is that carrier carries out further zone-refine with the high purity quartz boat, but because quartz can not produce induction heating, so before the heating of germanium energy autonomous induction, must have auxiliary heater heating to make germanium ingot temperature reach the temperature that germanium changes conductor into.Auxiliary heater is made ring-type by graphite material usually, adjacent with radio-frequency induction coil, together be enclosed within an end of quartz ampoule, in the induced field that radio-frequency induction coil produces, graphite annulus produces induced current and generates heat, thereby the germanium ingot in heated quarty tube and the pipe, germanium ingot temperature in the quartz ampoule termination is raise, and when germanium ingot temperature was elevated to about 900 ℃, the germanium ingot became conductor, remove auxiliary heater then, carry out zone-refine by high-frequency induction heating germanium ingot.Because heating-up temperature is up to 900 ℃, and be to heat under unprotect atmosphere, the heater of graphite material preparation can very fast oxidation and lost efficacy, and has influenced normally carrying out of producing.
Summary of the invention
The purpose of this invention is to provide carbon material heater and preparation method that a kind of surface has oxidation resistant coating.
At present, method commonly used is to adopt the chemical vapor deposition (CVD) legal system to be equipped with coating, and the characteristics that the CVD method prepares oxidation resistant coating are: the coating densification is smooth, purity is high, and can realize the design to coating structure, pattern, composition and thickness.Therefore, the CVD coating technology is widely used in semiconductor, metallurgy industry etc. with high temperature, highly purified various heat structure parts surface coatings, and is wherein extensive with the SiC coatings applications.It is bigger that SiC has chemical inertness, the excellent high-temperature mechanical performance, and thermal shock resistance and oxidation resistance, high fusing point, and also the reaction of SiC high-temperature oxydation can generate continuous, even, fine and close SiO
2The oxidation protection film is so SiC coating and SiC composite coating are the preferred material of carbon material oxidation resistant coating.
But the thermal coefficient of expansion of carbon/carbon compound material and graphite material and SiC coating does not match, and the coating of preparation and the associativity of matrix are relatively poor, come off easily, thereby the non-oxidizability of whole coating, thermal shock resistance is not ideal enough.
Silicon carbide whisker is that a kind of diameter is an extremely micron-sized mono-crystlling fibre of nanoscale, has good characteristics such as high strength, high rigidity, high elastic modulus and density are low, corrosion-resistant, chemical property stable, oxidation-resistance property is strong.
The present invention adopts following technical scheme to realize its goal of the invention, a kind of carbon material heater, and it comprises the matrix of being made up of carbon/carbon compound material or graphite material, the surface of matrix is provided with the transition zone of being made up of the silicon carbide whisker of growth in situ.
The present invention further improves anti-oxidation of coating, and transition zone is provided with the top layer of being made up of compact silicon carbide.
A kind of application of the heater of carbon material as mentioned above is to be used as auxiliary heater in the zone-refine of semi-conducting material.
A kind of preparation method of the oxidation resistant coating of carbon material as mentioned above, it may further comprise the steps:
⑴ get the raw materials ready: with the polishing of carbon material matrix, polishing, dry for standby after the washes clean;
⑵ Preparation of Catalyst: the presoma alcohol solution of preparation catalyst makes Ni in the solution
2+: Al
3+=(5~15): (1~3), the volume of ethanol accounts for 5%~20% of overall solution volume, adds aqueous solution of urea, regulates making Ni
2+Concentration be (0.05~0.2) mol/L, transfer in the reactor after stirring;
⑶ loading catalyst: step ⑴ gained matrix is put into reactor solution normal pressure dipping 5h~12h, react 1h~3h in the oil bath with 95 ℃~120 ℃ of reactor immersions then, after reactor is chilled to room temperature with cold water matrix is therefrom taken out, the back of drying in the shade at normal temperatures is stand-by;
⑷ growth in situ silicon carbide whisker: step ⑶ gained matrix is put into chemical vapor deposition stove; vacuumize; feed argon gas; under argon shield, heat up; depositing temperature is 950 ℃~1250 ℃; 10min~60min closes argon gas before arriving depositing temperature; feeding hydrogen reduces to catalyst; be incubated 10min~60min after reaching depositing temperature; then with hydrogen as carrier gas and diluent gas; flow-rate ratio is 1:1, with Bubbling method trichloromethyl silane is introduced in the cvd furnace, and the container bottle of splendid attire trichloromethyl silane places water bath with thermostatic control; 18 ℃~25 ℃ of bath temperatures; sedimentation time is 1h~50h, and pressure is normal pressure, prepares the transition zone of the silicon carbide whisker composition of growth in situ at matrix surface.
The present invention further improves anti-oxidation of coating, the top layer that preparation is made up of compact silicon carbide on the transition zone that silicon carbide whisker is formed, after the silicon carbide whisker deposition is finished, diluent gas is changed into argon gas, carrier gas is a hydrogen, and adjusts diluting gas flow and carrier gas flux than being 2:1, and depositing temperature is 950 ℃~1250 ℃, sedimentation time is 1h~50h, and pressure is normal pressure.
Owing to adopt technique scheme, the present invention has realized goal of the invention preferably, growth in situ one deck silicon carbide whisker on the carbon material heater, prepare fine and close carborundum skin again, thereby between the carborundum top layer of matrix and densification, form the SiCw transition zone, its thermal coefficient of expansion is between matrix and carborundum, can effectively reduce because the thermal stress that thermal coefficient of expansion does not match and produces, simultaneously, utilize extract bridging and the crackle of silicon carbide whisker to turn to mechanism to reduce crack size and quantity in the coating, help increasing substantially the antioxygenic property and the thermal shock resistance of coat of silicon carbide, and whole process of preparation can be finished continuously by chemical vapour deposition (CVD), simplified the preparation process of oxidation resistant coating greatly, can in semiconductor material regions is purified, use as auxiliary heater.
Description of drawings
Fig. 1 is that the present invention is at the structural representation of carbon material heater surface preparation by the transition zone of being made up of silicon carbide whisker;
Fig. 2 is the surface scan electromicroscopic photograph of the present invention at the silicon carbide whisker of carbon material heater surface in situ growth;
Fig. 3 is the X-Ray diffracting spectrum of the present invention at the silicon carbide whisker of carbon material heater surface in situ growth;
Fig. 4 is the cross section stereoscan photograph of the present invention at the silicon carbide whisker of carbon/carbon compound material heater surface in situ growth;
Fig. 5 is the present invention is reached the top layer of being made up of compact silicon carbide by the transition zone of being made up of silicon carbide whisker in carbon material heater surface preparation a structural representation;
Fig. 6 be the present invention when carbon material heater surface preparation has transition zone and top layer, the surface scan electromicroscopic photograph on top layer;
Fig. 7 is an embodiment of the invention 3(curve II), embodiment 4(curve III), embodiment 1(curve IV), embodiment 5(curve V) with SiC coating sample (curve I) isothermal oxidation weight loss curve in 1100 ℃ of air of traditional chemical vapour deposition process preparation;
Fig. 8 is an embodiment of the invention 3(curve II), embodiment 4(curve III), embodiment 1(curve IV), embodiment 5(curve V) with SiC coating sample (curve I) air of traditional chemical vapour deposition process preparation in 15 1100 ℃ * 3min of experience ← → the oxidation weight loss curve of room temperature * 3min thermal cycle;
Fig. 9 is an embodiment of the invention 6(curve II), embodiment 7(curve III), embodiment 2(curve IV), embodiment 8(curve V) with SiC coating sample (curve I) isothermal oxidation weight loss curve in 1100 ℃ of air of traditional chemical vapour deposition process preparation;
Figure 10 is an embodiment of the invention 6(curve II), embodiment 7(curve III), embodiment 2(curve IV), embodiment 8(curve V) with SiC coating sample (curve I) air of traditional chemical vapour deposition process preparation in 15 1100 ℃ * 3min of experience ← → the oxidation weight loss curve of room temperature * 3min thermal cycle.
Embodiment
The invention will be further described below in conjunction with drawings and Examples.
Embodiment 1:
As shown in Figure 1, a kind of carbon material oxidation resistant coating, it comprises the matrix of being made up of carbon/carbon compound material or graphite material 1, the surface of matrix 1 is provided with the transition zone of being made up of the silicon carbide whisker of growth in situ 2.
A kind of preparation method of the oxidation resistant coating of carbon material as mentioned above, it may further comprise the steps:
⑴ get the raw materials ready: with 1 polishing of carbon material matrix, polishing, dry for standby after the washes clean; The matrix 1 of present embodiment carbon material heater is a carbon/carbon compound material.
⑵ Preparation of Catalyst: the presoma alcohol solution of preparation catalyst makes Ni in the solution
2+: Al
3+=(5~15): (1~3) (present embodiment is Ni
2+: Al
3+=5:1), 5%~20%(present embodiment that the volume of ethanol accounts for overall solution volume is 20%), add aqueous solution of urea, regulate making Ni
2+Concentration for (0.05~0.2) mol/L(present embodiment be 0.1mol/L), transfer in the reactor after stirring;
⑶ loading catalyst: it is 10 h that step ⑴ gained matrix 1 is put into reactor solution normal pressure dipping 5h~12h(present embodiment), reacting 1h~3h(present embodiment in the oil bath with reactor immersion 95 ℃~120 ℃ (present embodiment is 110 ℃) then is 2h), after reactor is chilled to room temperature with cold water matrix 1 is therefrom taken out, the back of drying in the shade at normal temperatures is stand-by;
⑷ growth in situ silicon carbide whisker: step ⑶ gained matrix 1 is put into chemical vapor deposition stove; be evacuated to 0.1kPa; feed argon gas; under argon shield, heat up; depositing temperature is 950 ℃~1250 ℃ (present embodiment is 1100 ℃); 10min~60min(present embodiment is 15min before arriving depositing temperature) close argon gas; feeding hydrogen reduces to catalyst; hydrogen flowing quantity is that 100mL/min~300mL/min(present embodiment is 200mL/min); reach that to be incubated 10min~60min(present embodiment behind the depositing temperature be 15min); then with hydrogen as carrier gas and diluent gas; flow-rate ratio is 1:1; with Bubbling method trichloromethyl silane is introduced in the cvd furnace; the container bottle of splendid attire trichloromethyl silane places water bath with thermostatic control, and 18 ℃~25 ℃ of bath temperatures (present embodiment is 22 ℃), sedimentation time are that 1h~50h(present embodiment is 6h); pressure is normal pressure, the transition zone of being made up of the silicon carbide whisker of growth in situ in matrix 1 surface preparation 2.
A kind of application of the carbon material heater by method for preparing is to be used as auxiliary heater in the zone-refine of semi-conducting material.As in the monocrystalline germanium preparation, using.
Embodiment 2:
Present embodiment is in step ⑴, and the matrix 1 of carbon material heater is a graphite material.
Surplus with embodiment 1.
As shown in Figure 2, the silicon carbide whisker of the present invention's preparation is even in carbon material heater surface distributed.
As shown in Figure 3, the present invention is β-SiCw at the silicon carbide whisker of carbon material heater surface in situ growth.
As shown in Figure 4, when the present invention is carbon/carbon compound material at the matrix 1 of carbon material heater, cross section stereoscan photograph explanation silicon carbide whisker transition zone 2 porous and fine and close gradually along the direction of carbon/carbon composite material base body, this explanation transition zone 2 combines fine with matrix 1, simultaneously, transition zone 2 porous surfaces are when being provided with the top layer of being made up of compact silicon carbide thereon again, help alleviating the thermal stress of coating inside, avoid coating cracking and come off.
Embodiment 3:
As shown in Figure 5, the present invention further improves anti-oxidation of coating, is provided with the top layer of being made up of compact silicon carbide 3 on transition zone 2.
Its preparation technology is in step ⑴, and the matrix 1 of carbon material heater is a carbon/carbon compound material, and in step ⑷, sedimentation time is 2h.
After step ⑷ is intact, diluent gas is changed into argon gas, carrier gas is a hydrogen, and the adjustment diluting gas flow is 2:1 with the carrier gas flux ratio, depositing temperature is 950 ℃~1250 ℃ (present embodiment is 1100 ℃), and sedimentation time is that 1h~50h(present embodiment is 4h), pressure is normal pressure.The top layer 3 that preparation is made up of compact silicon carbide on the transition zone of being made up of the growth in situ silicon carbide whisker 2.
As shown in Figure 6, compact silicon carbide top layer 3 densifications, smooth are attended by a small amount of little crackle, but do not have tangible hole, compact silicon carbide top layer 3 be describeds in the evenly formation of silicon carbide whisker transition zone 2 surfaces, good compatibility are arranged between two-layer.
Surplus with embodiment 1.
Embodiment 4:
In step ⑷, sedimentation time is 3h, and during preparation top layer 3, sedimentation time is 3h.
Surplus with embodiment 1, embodiment 3.
Embodiment 5:
In step ⑷, sedimentation time is 5h, and during preparation top layer 3, sedimentation time is 1h.
Surplus with embodiment 1, embodiment 3.
As shown in Figure 7, the oxidation resistance of the SiC coating sample of traditional chemical vapour deposition process preparation is the poorest, and oxidation 10h weight-loss ratio is 41.11% in 1100 ℃ of air, among Fig. 7 shown in the curve I.
Oxidation 10h weight-loss ratio is respectively in 1100 ℃ of air of four embodiment coating samples of the present invention's preparation: 8.87%(embodiment 3, shown in the curve II), 5.50%(embodiment 4, shown in the curve III), 2.07%(embodiment 1, shown in the curve IV) and 0.87%(embodiment 5, shown in the curve V), its average weight-loss ratio is 4.33%.
As shown in Figure 8, the thermal shock resistance of the SiC coating sample of traditional chemical vapour deposition process preparation is the poorest, 1100 ℃ * 3min ← → 15 thermal cycles of room temperature * 3min after weight-loss ratio be 33.17%, among Fig. 8 shown in the curve I.
And four embodiment coating sample weight-loss ratios of the present invention's preparation are respectively: 11.09%(embodiment 3, shown in the curve II), 5.66%(embodiment 4, shown in the curve III), 0.51%(embodiment 1 is shown in the curve IV) and 0.22%(embodiment 5, shown in the curve V).
Embodiment 6:
As shown in Figure 5, the present invention further improves anti-oxidation of coating, is provided with the top layer of being made up of compact silicon carbide 3 on transition zone 2.
Its preparation technology is in step ⑴, and the matrix 1 of carbon material heater is a graphite material, and in step ⑷, sedimentation time is 2h.
After step ⑷ is intact, diluent gas is changed into argon gas, carrier gas is a hydrogen, and the adjustment diluting gas flow is 2:1 with the carrier gas flux ratio, depositing temperature is 950 ℃~1250 ℃ (present embodiment is 1100 ℃), and sedimentation time is that 1h~50h(present embodiment is 4h), pressure is normal pressure.The top layer 3 that preparation is made up of compact silicon carbide on the transition zone of being made up of the growth in situ silicon carbide whisker 2.
Surplus with embodiment 1.
Embodiment 7:
In step ⑴, the matrix 1 of carbon material heater is a graphite material, and in step ⑷, sedimentation time is 3h, and during preparation top layer 3, sedimentation time is 3h.
Surplus with embodiment 1, embodiment 6.
Embodiment 8:
In step ⑴, the matrix 1 of carbon material heater is a graphite material, and in step ⑷, sedimentation time is 5h, and during preparation top layer 3, sedimentation time is 1h.
Surplus with embodiment 1, embodiment 6.
As shown in Figure 9, the oxidation resistance of the SiC coating sample of traditional chemical vapour deposition process preparation is the poorest, and oxidation 10h weight-loss ratio is 32.82% in 1100 ℃ of air, among Fig. 9 shown in the curve I.
Oxidation 10h weight-loss ratio is respectively in 1100 ℃ of air of four embodiment coating samples of the present invention's preparation: 8.63%(embodiment 6, shown in the curve II), 5.36%(embodiment 7, shown in the curve III), 2.03%(embodiment 2, shown in the curve IV) and 0.85%(embodiment 8, shown in the curve V), its average weight-loss ratio is 4.22%.
As shown in Figure 10, the thermal shock resistance of the SiC coating sample of traditional chemical vapour deposition process preparation is the poorest, 1100 ℃ * 3min ← → 15 thermal cycles of room temperature * 3min after weight-loss ratio be 28.83%, among Figure 10 shown in the curve I.
And four embodiment coating sample weight-loss ratios of the present invention's preparation are respectively: 10.83%(embodiment 6, shown in the curve II), 5.54%(embodiment 7, shown in the curve III), 0.49%(embodiment 2 is shown in the curve IV) and 0.21%(embodiment 8, shown in the curve V).
The SiC coating for preparing for the ease of the coating of relatively the present invention's preparation and traditional chemical vapour deposition process is in the difference aspect antioxygenic property and the thermal shock resistance, the sedimentation time of all embodiment floating coats of the present invention is identical, and promptly the sedimentation time of the sedimentation time of growth in situ silicon carbide whisker or growth in situ silicon carbide whisker and fine and close SiC coating sedimentation time sum are 6h.
The present invention is by matrix 1 surface preparation growth in situ SiCw coating and the toughness reinforcing SiCw-SiC coating of SiCw at carbon/carbon compound material or graphite material heater, the non-oxidizability of coating and thermal shock resistance height, realized the coating preparation of serialization under the normal pressure, preparation technology is simple, can use as auxiliary heater in semiconductor material regions is purified.