Research On Fabricating Amorphous Alloys By Bar Material Plasma Spray

Amorphous alloy is a kind of materials with good intension, toughness, corrosion resisting ability, good magnetism performances, and the wear-resisting property is better than crystal alloy, and it has been paid more and more attention by the scientists of materials science and the engineers. but this kind of materials can only be made under non-equilibrium conditions, and the machining property is not very good, so the development and application of amorphous alloy was counteracted. the method of plasma spray can provide a very high heat up speed and spur speed, and the flames have a high temperature grads, so the method can provide a suitable conditions for making amorphous alloys. Mr Xiang Xinghua has made amorphous alloy coating of amorphous alloy powders by plasma spray. But the method of making amorphous alloy by crystal materials has not been reported yet. In reflection to the work has been done of the amorphous fabrication, we studied a method of making amorphous alloy powders and coatings by bar materials plasma spray. It provided a new method for making amorphous alloy, and offered theoretical basis for fabricating and application of amorphous alloy by the method.The plasma spray equipment we used is GP-80, put the metal bar forward to the gunpoint of the plasma gun by the home-made bar sender. and the metal bar was melt and spurted to a revolving copper bar to form amorphous powders sheets, and if it was spurted to coarse surfaces of copper or Q235 steel,it will formed a amorphous alloy coating. The best parameters was selected by experiment, and the microstructures, bone strength, microhardness, crystallization degree was tested by X ray diffraction instrument ,universal test machine, microhardness tester,differential thermal analyzer. And the process of heating up and speed up rule was simulated by numerical analysis.The results of the experiment showed that the we have fabricated amorphous alloy powders and coatings with high amorphous content successfully, the micro hardness is 957HV₂₅-1187HV₂₅; The bone strength between the substrate and the coating is about 30Mpa, the bonding between the coating and the matrix is mechanical and metallurgical. the crystallization temperatures of the amorphous alloys fabricated by Fe₇₉Si₁₀B₁₁,Fe₈₀P₁₃C₇ and Fe₇₂Cr₈P₁₃C₇ bar are 531℃,433℃,459℃. So they are thermally stable materials; the results of simulation agree with the tested results very well, so the method that stimulate the velocity and temperature of the particles during the spray process by hydrokinetics, the theories of gas-solid particles flew and and the model of convective heat transfer is feasible. the results of the numerical analysis shows that: the process of speed up and heat up is very fast; the temperature gradient and speed gradient of the particles during the spray process are very high. and the cooling velocity of the particles with the diameter of 20μm is 1.612×10⁸K/s.