Titanium rod and titanium wire are easy to react with O,H,N and other elements in the air and Si,AL,Mg and other elements in the embedded material at high temperature, forming a surface pollution layer on the surface of the casting, making its excellent physical and chemical properties become worse, hardness increase, plasticity, elasticity decrease, brittleness increase.
The density of titanium rod and wire is small, so the inertia of titanium liquid is small.The temperature difference between casting temperature and casting mold (300 ° c) is large, cooling is fast, casting is carried out in a protective atmosphere, and defects such as porosity are unavoidable on the surface and inside of titanium casting, which have a great influence on casting quality.
Therefore, the surface of titanium titanium rod and wire processing compared with other titanium products is more important, due to the unique physical and chemical properties of titanium wire, such as small coefficient of thermal conductivity, surface hardness, and low modulus of elasticity, viscosity, low conductivity, easy oxidation, etc., the surface treatment of titanium has brought a lot of difficulty, the conventional surface treatment is very difficult to achieve the ideal effect.Special processing methods and means of operation must be adopted.
The surface modification of titanium rod and wire mainly includes nitriding, anodic oxidation, atmospheric oxidation, etc.
1. Nitriding: the chemical heat treatment technology including plasma nitriding, multi-arc ion plating, ion implantation and laser nitriding is adopted to form golden TIN nitriding coating on the surface of titanium denture, so as to improve the wear resistance, corrosion resistance and fatigue resistance of titanium.However, due to the complicated technology and expensive equipment, the surface modification of titanium denture is difficult to achieve clinical application.
2. Anodic oxidation: the anodic oxidation technology of titanium rod is relatively easy. Under the action of applied voltage in some oxidizing media, the titanium anode can form a thick oxide film, thus improving its corrosion resistance, wear resistance and weather resistance.Anodized electrolytes are generally H2SO4 and aqueous organic acids.
3. Atmospheric oxidation: titanium rod can form a thick and firm anhydrous oxidation film in the high temperature atmosphere, which is relatively simple for the overall corrosion and gap corrosion of titanium.