Research On Double Glow Plasma Carburizing On ZrTiAlV Alloy Surface And Their Properties

Since zirconium alloys have small thermal neutron absorption cross section, highthermal conductivity and good workability as important spatial structure materials, whichhas been widely used in the cladding of nuclear fuel, the end plug and core materials. Thecorrosion resistance is superior to other alloys. However, they are restricted in applicationsbecause of their low hardess and poor wear resistance. In this discussion, carburizing onthe surface of Zr53Ti39Al4V4（Zr50）, Zr17Ti72Al7V4（Zr20） and Zr11Ti80Al5V4（Zr10）was used through double glow plasma surface alloying technique to improve surface wearresistance. Moreover, the properties of the diffusion layer and the variation with Zr contentare investigated.The modified surface layers on ZrTi alloy were obtained by using the double glowplasma surface alloying technique. Orthogonal test method was used to optimize sourcevoltage, workpiece voltage, electrode distance, pressure and other process parameters ofcarburizing. Taking advantage of XRD and EDS detection means to analysize thecarburized layer, the diffusion layer thickness of Zr10alloy, Zr20alloy and Zr50alloy was5μm,10μm and17μm, respectively. New phases TiC and ZrC were formed on the surface.So the surface microhardness was up to1500HV. The microstructure is composed of αphase and β phase before and after carburizing. With Zr content, the ration of length todiameter of α phase increased.Through the study of the friction and wear performance of carburizing layer andcorrosion resistance test, it learned that the friction coefficient of the matrix decreased asthe Zr content increased. The friction coefficient after carburizing declined at differentdegrees owing to the existence of surface carbides. There was little change betweenquench aging and after carburizing. Abrasive wear and adhesive wear were two mainmechanisms. The wear scar became smooth and the roughness decreased aftercarburizing with increasing in Zr content. The changing trend of wear rate was consistentwith the friction coefficient and hardness. At5%H₂SO₄solution, the corrosion currentdensity of diffueion layer for the three alloys was two orders of magnitude smaller than the matrix. The corrosion resistance was greatly improved. They showed the same rolesin3.5%NaCl and0.5mol/L HCl solutions, the corrosion potential and corrosion currentdensity of Zr20alloy was smaller than Zr10alloy and Zr50alloy. No passivationoccurred. So Zr20alloy showed better corrosion resistance.