Preparation And Properties Of Zirconia Coatings On The Surface Of TiNi Alloy

TiNi alloy is considered as one of the best biomaterials in modern medicine because of its excellent mechanical properties and good biocompatibility.It has small elastic modulus,good resilience and good formability.TiNi shape memory alloy has an expansion rate of more than 20%,a fatigue life of up to 107 times,and a damping characteristic 10 times higher than that of ordinary springs.It is widely used in dental and orthopedics medical fields.TiNi alloy orthodontic wire can provide continuous and gentle orthodontic force to push the teeth,but long-term storage and complex oral environment,the dissolution of nickel ions may cause allergic reactions,and the metallic color can also damage the image of patients.At present,the method to solve this problem at home and abroad is to prepare the tooth color polymer film on the surface of the alloy.However,the polymer film has short service life,low hardness and poor wear resistance,so it is urgent to develop a new film to solve the above problems.We use high-vacuum magnetron sputtering technology to prepare Zr films on the surface of titanium-nickel substrates,and optimize and adjust the sputtering bias,power and time parameters.We further applied electrochemical anodization to the deposited Zr coating to obtain a ZrO₂ ceramic coating on the surface of the titanium-nickel alloy substrate.We further control the uniformity and roughness of the ZrO₂ coating by controlling the oxidation time and voltage,aiming to obtain a uniform and dense ZrO₂ceramic coating.Through the morphology characterization(SEM),phase analysis(XRD)and related tests and analysis of friction and corrosion resistance of the material,we found that the sputtering bias can affect the bonding force between the Zr coating and the surface of the titanium nickel substrate.With the gradual increase of the sputtering bias,the particle size of the Zr coating also increases,and the shape also changes significantly;the sputtering time mainly affects the particle size and thickness of the Zr coating,and is positively correlated with it.XRD phase analysis showed that the ZrO₂ film after anodizing surface treatment was mainly composed of m-ZrO₂ and a small amount of t-ZrO₂.The electrochemical anodization voltage increased,and the thickness and roughness of the coating increased first and then decreased.The oxidation time is negatively related to the roughness of the coating and positively related to the hardness.The bonding force between the ZrO₂ coating and the substrate is mainly related to the related parameters of magnetron sputtering,and the correlation with anodic oxidation is not obvious.Based on the comprehensive analysis of the relationship between the structure and properties of the preparation process,the optimum process parameters were determined.Magnetron sputtering process:sputtering bias-130V,sputtering power 150W-200W,deposition time 120min-180min;Anodic oxidation process:the electrolyte is an aqueous solution of ethylene glycol and ammonium fluoride,the temperature is room temperature,the oxidation voltage is 20V,and the oxidation time is 10min.