Titanium plate and Medical titanium rod The surface reaction layer is the main factor affecting the physical and chemical properties of titanium workpiece. Before processing, the surface contamination layer and defect layer must be completely removed. Physical mechanical polishing of titanium plate and titanium rod surface polishing process:

1. Sand blasting:

Medical titanium wire White corundum is generally used for sand blasting of castings. The pressure of sand blasting is smaller than that of non precious metals, and is generally controlled below 0.45MPa. Because when the spraying pressure is too high, the sand particles will impact the titanium surface and produce intense sparks. When the temperature rises, it can react with the titanium surface, forming secondary pollution and affecting the surface quality. The time is 15-30 seconds, and only the sand, sintering layer and partial oxide layer on the surface of the casting can be removed. The remaining surface reaction layer structure should be rapidly removed by chemical pickling.

2. Pickling:

Pickling can quickly and completely remove the surface reaction layer, and the surface will not be polluted by other elements. Both HF-HCL and HF-HNO3 pickling solutions can be used for titanium pickling, but HF-HCL pickling solutions absorb more hydrogen, while HF-HNO3 pickling solutions absorb less hydrogen, which can control the concentration of HNO3 to reduce hydrogen absorption, and can brighten the surface. Generally, the concentration of HF is about 3% - 5%, and the concentration of HNO3 is about 15% - 30%.

The surface reaction layer of titanium plate and titanium rod can be completely removed by the method of acid cleaning after sand blasting.

In addition to physical and mechanical polishing, there are two kinds of reaction layers on the surface of titanium plate and titanium rod: 1. chemical polishing, 2. electrolytic polishing.

1. Chemical polishing:

During chemical polishing, the purpose of leveling and polishing is achieved through the oxidation and reduction reaction of metal in the chemical medium. The advantage of chemical polishing is that it has nothing to do with the hardness of metal, polishing area and structural shape. All parts in contact with the polishing solution are polished without special complex equipment. It is easy to operate and is more suitable for polishing complex titanium denture brackets. However, the process parameters of chemical polishing are difficult to control. It is required to have a good polishing effect on dentures without affecting the precision of dentures. A better chemical polishing solution for titanium is HF and HNO3 prepared in a certain proportion. HF is a reducing agent, which can dissolve titanium metal and play a leveling role. When the concentration is less than 10%, HNO3 acts as an oxidant to prevent excessive dissolution of titanium and hydrogen absorption, and can also produce a bright effect. Titanium polishing solution requires high concentration, low temperature and short polishing time (1~2min).

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