A kind of preparation method of plasma spraying insulating coatingTechnical field
The invention belongs to field of surface treatment, are related to a kind of preparation method of plasma spraying insulating coating.
Background technology
Plasma spraying belongs to one kind of thermal spraying sufacing, is made using the plasma that anode and cathode arc discharge generatesFor heat source, matrix formation coating is hit after accelerating sprayed on material by means of high speed plasma jet.The temperature height of plasma flame flow,Energy is concentrated, and is very suitable for preparing various high-melting-point ceramic coatings.Melt granules deform fully when being collided with part, and coating causesIt is close, surfacing is smooth, high with the bond strength of matrix.Plasma spraying technology is the economy that piece surface is strengthened and protected in advanceAnd effective method, surface can be assigned with the multiple functions such as wear-resisting, anti-corrosion, resistance to high temperature oxidation, be widely used in aerospace, stoneEach industrial circle such as oily natural gas, steel.
In commercial Application, from simple exhaust ventilation to complicated, extra heavy high ferro motor-car, it is frequently run onto electricityErosion problem.Galvanic corrosion is that electric current flows through a kind of electrodisintegration form caused by the components such as bearing.When electric current flows through part, since electric discharge is madeWith, the pitting that a large amount of diameters only have several microns can be formed in part surfaces externally and internally, will soon be failed due to abrasion, increase dimensionAccomplish this, or even causes huge economic losses.With the extensive use of frequency converter, the galvanic corrosion problems getting worse of part.In addition,The resistance heater of new-energy automobile uses ptc material to heat under normal conditions at present, and heating region need to be reached with external environmentTo very high-grade electrical isolation, if there is a certain amount of leakage current, resistance heater is possible to the feelings such as excess temperature occur, conductShape causes resistance heater to collapse, and self-burning of vehicle is caused when serious.
In order to capture technical barrier present in application at present, developing can keep the attribute of material matrix itself specialSign, moreover it is possible to the technology of electrical isolation protection be provided, there is very important practical significance.
Invention content
The purpose of the present invention is improve a kind of preparation of plasma spraying insulating coating of electric elements surface insulation performanceMethod.The characteristics of coating has a good insulation performance, and preparation technology of coating is simple, electric heating excellent insulation performance.
The technical scheme is that so realize：A kind of preparation method of plasma spraying insulating coating, it is described etc.Using being containing 99% or more high purity aluminium oxide powder, the grain size of alumina powder divides the coating of plasma spray insulating coatingCloth range is between 5-90 μm.Being prepared using plasma spraying has dystectic insulating coating material.Transition zone is Ni-based conjunctionGolden material.There is the two good matched coefficients of thermal expansion, coating to have good bond strength.
The present invention can provide the method that plasma spraying prepares insulating coating, and this approach includes the following steps：
1. matrix is checked, is cleared up as required；
2. carrying out the pre-heat treatment to matrix；
3. using gas based on argon gas, gas supplemented by hydrogen.By adjusting the gas flow of argon gas and hydrogen, change plasma flame flowTemperature and speed.If the gas flow of argon gas is 20-70 NLPM, the gas flow of hydrogen is 1-10 NLPM.Pass through electric currentThe temperature of controllable plasma flame flow, electric current 300-600A.By adjusting the gas flow of carrier gas, powder is sent to flame streamCenter, carrier gas flux 1-10NLPM, powder sending quantity 10-200g/min.Spray distance is 50-200mm.Spraying 2-30 times, absolutelyThe thickness of edge coating is 20-600 μm；
4. carrying out electrical insulation capability test to insulating coating, insulation resistance is more than 8G Ω, and anti-pressure resistance breakdown voltage is more than 5000V.
The present invention is mainly the insulation performance for solving the problems, such as electric vehicle appliance element surface.The coating compactness of preparationGood, no cofusing particle is less, and electrical insulation capability is excellent.The excellent of the present invention is the reasonable science of the preparation method, easy to operate, easilyIn implementation, convenient for large-scale production.
Specific implementation mode
A kind of preparation method of plasma spraying insulating coating, the coating of the plasma spraying insulating coating, which uses, isContaining 99% or more high purity aluminium oxide powder, the particle size distribution range of alumina powder is between 5-90 μm.Using plasmaPrepared by spraying have dystectic insulating coating material.Matrix is nickel-bass alloy material.The present invention can provide plasma sprayThe method that painting prepares insulating coating, this approach includes the following steps.
1. matrix is checked, is cleared up as required.
2. carrying out the pre-heat treatment to matrix using plasma flame flow.
3. using gas based on argon gas, gas supplemented by hydrogen.By adjusting the gas flow of argon gas and hydrogen, change flame passesThe temperature and speed of stream.If the gas flow of argon gas is 20-70 NLPM, the gas flow of hydrogen is 1-10 NLPM.Pass through electricityFlow the temperature of also controllable plasma flame flow, electric current 300-600A.By adjusting the gas flow of carrier gas, powder is sent to flameThe center of stream, carrier gas flux 1-10NLPM, powder sending quantity 10-200g/min.Spray distance is 50-200mm.Spray 2-30Time.
4. after the completion of spraying, the thickness for measuring insulating coating is 20-600 μm.
Electrical insulation capability test is carried out to insulating coating, insulation resistance is more than 8G Ω, and anti-pressure resistance breakdown voltage is more than5000V.Metallographic Analysis is carried out to the insulating coating after spraying, coating porosity is in 0.5-12%.To the insulating coating after sprayingMicro-hardness testing is carried out, hardness number is in 300-1100 HV300.