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How to deal with the surface defect reaction layer of titanium alloy plate and titanium alloy rod

The reaction layer on the surface of titanium plate and titanium rod is the main economic factor affecting the performance of physical and chemical system of titanium workpiece. Surface contamination and defect layers must be completely removed before processing. Physical and mechanical polishing of titanium plate and surface polishing of titanium rod;

1, sand blasting:
Sandblasting ability analysis of titanium wire castings, generally we can choose white corundum to spray better, generally need time to control below 0.45mpa, because the pressure of sandblasting is smaller than that of non-precious metals. When the pressure of injection system is too high, the temperature rise will react with the titanium surface to form secondary environmental pollution, and the impact of sand particles on the titanium surface will produce competitive sparks, affecting the surface engineering quality. The time is 15-30 seconds, only remove the castings to stick sand on the surface, different sintered layers on the surface and some students can study the oxide layer. The remaining part of the surface reaction layer was quickly removed by conventional chemical pickling.

2, pickling:
Pickling can quickly and thoroughly remove the surface reaction layer without contaminating other elements. Hf-hcl and HF-HNO3 acid washing solution can be used for titanium pickling, but HF-HCl acid washing solution has a large hydrogen absorption capacity, while HF-HNO3 acid washing solution has a small hydrogen absorption capacity, which can control the concentration of HNO3, reduce hydrogen absorption, and make the surface bright. Usually, HF concentration is about 3%-5% and HNO3 concentration is about 15%-30%.

Acid cleaning after sandblasting can completely remove the reaction layer on the surface of titanium plate and titanium rod.

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

1, chemical polishing:
By analyzing and studying the oxidation technology of metal in chemistry teaching environment, an enterprise reaction can be reduced to achieve the purpose of leveling and polishing. Its advantage is that chemical polishing does not depend on metal hardness, polishing area and different structure shape information, and all parts in contact with polishing fluid are polished. In special cases, no complex network equipment is needed, and the operation method is simple, which is more suitable for polishing denture brackets of various complex system structures. However, it is difficult to manage and control the technical parameter data of chemical polishing process, which requires that we can have good polishing work learning effect on the denture without affecting the machining accuracy. The better chemical polishing solution is HF and HNO3, which can be prepared in a certain time. Hf is a reducing agent, which can dissolve titanium metal and play a role of leveling and concentration.

2, electrolytic polishing:
Because the conductivity of titanium alloy tube is relatively low, also known as electrochemical polishing or anodic solution polishing, oxidation technology performance is very strong, using hF-H3PO4, HF-H2SO4 and other acidic aqueous electrolyte can hardly polish titanium, applied voltage, titanium anode oxidation immediately, anodic dissolution can not be carried out. Anhydrous chloride electrolyte has a good polishing effect on titanium at low voltage. Mirror polishing is feasible for small samples, but for complex restorations, mirror polishing cannot achieve complete polishing. This problem can be solved by changing the shape of the cathode and adding a cathode. Further research is needed.
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