First, wear-resistant surface treatment
Wear resistance is a major disadvantage of titanium metal, which is prone to defects such as pitting. Titanium surface treatment methods include Cr plating, Ni plating wet coating method, sputtering method, overlay welding method, thermal diffusion method, etc., and more advanced surface strengthening methods such as CVD, PVD, and PVCD.
1. Wet coating is an effective wear-resistant surface treatment method, which is first plated with Ni and then with Cr. The electroforming method has a high film formation speed and a thickness of several micrometers.
2. The sputtering method utilizes a plasma jet high-speed air jet to spray the molten metal onto the surface of the material to be treated without vacuum and high efficiency.
3. The surfacing method utilizes a plasma transfer arc to weld harden the surface of the titanium to have wear resistance. It is suitable for handling large and thick large workpieces. It is simple in method and does not need to be exposed at high temperature to prevent mechanical properties from deteriorating.
4. The thermal diffusion method is mainly used for the hardening process of steel materials such as carburizing, nitriding, boriding and the like. The ion nitriding method is different from gas nitriding. The ion nitriding uses a glow discharge plasma to destroy the oxide film on the titanium surface, and the efficiency is high. In recent years, it has been used for titanium, the temperature reached 850 degrees Celsius, the thickness of the nitride film increased from 0.7 micron to 5.0 micron, the surface hardness reached 1200-1600Hv, and the wear resistance was good.
Second, the corrosion resistance surface treatment Generally, the corrosion resistance surface treatment of titanium metal and titanium alloy is to prevent the corrosion of titanium in a non-oxidizing acid aqueous solution such as sulfuric acid or hydrochloric acid which is highly corrosive. Therefore, the surface treatment method is as follows:
1. Atmospheric oxidation treatment Titanium metal and alloy are placed in a high temperature atmosphere, the oxide film will be thickened, and the thickness will increase with time and temperature, so that the overall corrosion and crevice corrosion of titanium is placed, the method is simple, but the durability is not high. And there are atmospheric oxidation treatment conditions, temperature and time guarantee.
2. The oxide film coated with noble metal can protect the titanium from corrosion. The formula for the formation of the oxide film is: Ti +2H2O date→TiO2 +4H+ +4e?/P> The reaction is an anodic reaction, which can increase the potential of titanium. This reaction proceeds to improve the oxide film stability and corrosion resistance of titanium. When the area is large, it is difficult to apply a uniform voltage, and this method is not applicable. Precious metals are also less susceptible to corrosion in harsh environments and exhibit high potentials. Therefore, the surface of the titanium metal is coated with a precious metal to effectively improve its corrosion. It is usually coated with palladium (Pd) and ruthenium (Ru) and their oxides, and the corrosion resistance is very good.
3. Dry process coating TiC, TiN film (CVD, PVD, PCVD) TiC, TiN and TiCN are better than Ti, and the methods are gas method, CVD, PVD, PCVD, which are far above the titanium phase transition point. When heated at a temperature, the structure and shape of the product are changed to cause the product to fail to meet the requirements for use. The CVD, PVD, and PCVD methods require special equipment and are costly. Generally, such methods are not used to improve corrosion resistance, and occasionally are used to improve wear resistance.
Third, the craftsmanship surface treatment, so the surface treatment of the craftsmanship, mainly because titanium metal is widely used in building materials, watches, glasses and other decorations, the use of titanium metal is mainly to use its excellent corrosion resistance, but the jewelry needs a bright surface, luster Stylish, so it is necessary to carry out craftsmanship.
1. Surface finishing 1 grinding; 2 annealing and pickling, the surface is tarnished, gray; 3 vacuum annealing + pickling, the surface is dark gray; 4 shot peening (50-500 micron glass beads), the surface is pear-like ; 5 dense stripe processing, 150-240 # abrasive belt grinding, so that it has long and continuous grinding stripes; 6 pattern imprinting processing, that is, concave and convex processing, processing surface has concave and convex relief pattern; 7 chemical etching pattern.
2, mirror finishing
For titanium materials, mirror finishing is more difficult. 1 soft belt polishing, hard surface on the surface is low efficiency; 2 chemical polishing, affected by temperature, time, polishing liquid factors; 3 electrolytic polishing, anhydrous organic electrolyte has a good electropolishing effect on titanium.
3. Coloring The surface of titanium is silver white, and the coloring treatment usually includes atmospheric oxidation, anodizing, and chemical treatment.