Research On The Preparation And Properties Of Surface Ti-Pd Alloyed Layer On Pure Titanium

Titanium palladium alloy has excellent corrosion resistance, which is higher thanpure titanium in reductive acid, and it has higher crevice corrosion resistance than puretitanium. But it is expensive, because of titanium palladium alloys containing noblemetal palladium, which limits its further application.The surface engineering technology, preparation of Ti-Pd alloyed layer on thetitanium surface can reduce cost and improve the performance of the corrosionresistance. This paper introduces two methods of preparation Ti-Pd alloyed layer ontitanium surface. The two methods are glow plasma surface Palladizing on titanium, andPd film deposited on titanium+thermal diffusion.By using XRD, SEM, EDS and other analytical methods, the phase composition,microstructure, composition distribution of Ti-Pd alloyed layer are analyzed. And theresearch focuses on the diffusion behavior of Pd in Ti to propose the formationmechanism of Ti-Pd alloyed layer, and the corrosion resistance of Ti-Pd alloyed layerwhen it is in the strong reductive acid. We draws the following conclusions:1. Glow plasma surface Palladizing on titanium: at900℃, the diffusion behaviorof Pd in Ti belongs to the reaction diffusion, so the alloyed layer has a multilayerstructure. At1000℃, the diffusion behavior of Pd in Ti belongs to the single phasesolid solution diffusion, so the alloyed layer is a single layer structure.2. Pd film deposited on titanium+thermal diffusion: when heated at500℃~800℃, the diffusion behavior of Pd in Ti belongs to the reaction diffusion, so alloyedlayer has a multilayer structure. When heated at900℃, the diffusion behavior of Pd inTi belongs to the single phase solid solution diffusion, so the alloyed layer is a single layer structure.When heated at1000℃, the diffusion behavior of Pd in Ti belongs tothe single phase solid solution diffusion, so the alloyed layer is a "strip" structure.3．After the Ti-Pd alloyed layer prepared by two methods at900℃~1000℃inthe same time, the structures and contents are very different. The fundamental reasonis that during glow plasma alloying process, Pd everfount sputters out from theelectrode source, and it constantly increases. But during Pd film depositing on titanium+thermal diffusion process, which the thickness identified, the Pd during the thermaltreatment is limited supply, so the amount of Pd is invariant.4. The corrosion resistance of Ti-Pd alloyed layer prepared by two methods in37%HCl and80%H2SO4is both two orders of magnitude higher than the pure titanium.We establish the corrosion and protection mechanism model of Ti-Pd alloyed layer inHCl and H2SO4.5. In the same time’s treatment at900℃~1000℃, the Ti-Pd alloyed layerprepared by Pd film deposited on titanium+thermal diffusion is thicker than the Ti-Pdalloyed layer prepared by glow plasma surface Palladizing on titanium, and the Pdelement content in the former method is lower. This method can save precious metal,and reduce the cost, so it is an efficient method to make the Ti-Pd alloyed layer form onthe surface of titanium with low cost.