Solution of dealing with the surface defect reaction layer of titanium alloy plate and titanium alloy rod

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

Sand blast

The sandblasting treatment of titanium wire cast parts is generally selected white corundum spray is better, the pressure of the sandblasting body is smaller than the non-precious metals, generally controlled below 0.45MPa. Because, when the injection pressure is too large, the sand particle shocks the titanium surface to produce fierce sparks, the temperature increase can react with the titanium surface, forming a secondary pollution, affecting the surface quality. The time is 15-30 seconds, only remove the sticky sand on the casting surface, surface sintering layer and partial oxide layer can be removed. The rest of the surface reaction layer structure should be quickly removed by the chemical pickling method.

Acid pickling 

Acid washing can quickly and completely remove the surface reaction layer without the surface causing contamination of other elements. HF-HCL and HF-HNO3 series can be used for titanium pickling, but HF-HCL series hydrogen absorption amount, and HF-HNO3 series hydrogen absorption is small, can control the concentration of HNO3 to reduce hydrogen absorption, and the surface light treatment, the concentration of HF concentration of about 3% -5%, HNO3 concentration of about 15% -30% is appropriate.

The surface reaction layer of titanium plate and titanium rod can completely remove the titanium surface reaction layer by pickling after sandblasting.

In addition to physical and mechanical polishing, there are two surface reaction layers of titanium plate and titanium rod, respectively, namely: 1. Chemical polishing, 2. Electrolysis polishing.

Chemical polishing 

The purpose of the chemical polishing is achieved by the redox reaction of the metal in the chemical medium. Its advantage is that chemical polishing and the hardness of the metal, polishing area has nothing to do with the shape of the structure, all the parts in contact with the polishing liquid are polished, without special complex equipment, easy to operate, more suitable for the polishing of the complex structure titanium denture bracket. However, the process parameters of chemical polishing are more difficult to control, which requires a good polishing effect of the denture without affecting the accuracy of the denture. Better titanium chemical polishing liquid is HF and HNO3 prepared according to a certain proportion, HF is a reducing agent, can dissolve titanium metal, play a leveling effect.

Electropolishing 

Also known as electrochemical polishing or anode dissolution polishing, because of the electrical conductivity of titanium alloy tube is low, extremely strong oxidation performance, the use of water acid electrolyte such as HF-H3PO4, HF-H2SO4 series electrolyte to titanium almost cannot polishing, after applying the external voltage, titanium anode immediately oxidation, and the anode dissolution can not be carried out. However, the use of anhydrous chloride electrolyte at low voltage, has a good polishing effect on titanium, small specimens can get mirror polishing, but for complex repair still can not achieve the purpose of complete polishing, perhaps using the change of cathode shape and additional cathode method to solve this problem, it needs to be further studied.