ASTMB265 titanium plate surface defects reaction layer how to deal with

ASTMB265 titanium plate surface reaction layer is the main factor affecting the physical and chemical properties of titanium workpieces, before processing, must achieve complete removal of surface contamination layer and defective layer. Titanium plate and bar surface
Physical mechanical polishing process:
1, sandblasting:
Titanium wire castings sandblasting treatment is generally better to use white corundum spray, sandblasting pressure to be smaller than non-precious metals, generally controlled at 0.45MPa below. Because, the spray pressure is too large
When the sand particles impact on the surface of titanium to produce intense sparks, elevated temperature can react with the surface of titanium, the formation of secondary pollution, affecting the surface quality. Time for 15-30 seconds, only to remove the casting surface
The time is 15-30 seconds, only to remove the sticky sand on the surface of the casting, the surface sintered layer and part of the oxidized layer can be. The rest of the surface reaction layer structure is appropriate to use chemical pickling method to quickly remove.
2. Acid washing:
Acid washing can quickly and completely remove the surface reaction layer, and the surface will not produce other elements of pollution. HF-HCL system and HF-HNO3 system pickling solution can be used for titanium pickling, but HF-HCL system pickling solution can be used for titanium pickling, but HF-HCL system pickling solution can be used for titanium pickling.
F-HCL system pickling solution has a larger amount of hydrogen absorption, while HF-HNO3 system pickling solution has a small amount of hydrogen absorption, the concentration of HNO3 can be controlled to reduce the absorption of hydrogen, and the surface can be brightening treatment, generally the HF
Generally, the concentration of HF is about 3%-5%, and the concentration of HNO3 is about 15%-30%.

The reaction layer on the surface of titanium plate and bar can be completely removed by the method of acid washing after sand blasting.
Titanium plate and titanium bar surface reaction layer in addition to physical mechanical polishing there are two kinds, respectively: 1. chemical polishing, 2. electrolytic polishing.
1, chemical polishing:
Chemical polishing through the metal in the chemical medium of redox reaction and achieve the purpose of leveling and polishing. The advantage is that chemical polishing and metal hardness, polishing area and structure shape
Its advantage is that chemical polishing and metal hardness, polishing area and structure shape has nothing to do, where the parts in contact with the polishing solution are polished, without special complex equipment, easy to operate, more suitable for complex structure of titanium denture bracket polishing. But the chemical polishing process
However, chemical polishing process parameters are more difficult to control, the requirements of the denture without affecting the accuracy of the denture can have a good polishing effect on the denture. The better titanium chemical polishing solution is HF and HNO3 prepared in a certain proportion.
HF is a reducing agent, can dissolve titanium metal, play a leveling effect, the concentration of <10%, HNO3 play an oxidizing role, to prevent excessive dissolution of titanium and hydrogen absorption, and at the same time can produce a bright effect. Titanium
Polishing solution requires high concentration, low temperature, short polishing time (1 ~ 2min).
2, electrolytic polishing:
Also known as electrochemical polishing or anodic dissolution polishing, due to the low conductivity of titanium alloy tube, oxidation properties are extremely strong, the use of aqueous acidic electrolyte such as HF-H3PO4, HF-H2
SO4 electrolyte on titanium can hardly be polished, after applying external voltage, the titanium anode immediately oxidized, and the anode dissolution can not be carried out. However, the use of anhydrous chloride electrolyte at low voltage.
However, the use of anhydrous chloride electrolyte at low voltage, titanium has a good polishing effect, small specimens can be obtained mirror polishing, but for complex restorations still can not achieve the purpose of complete polishing, perhaps by changing the shape of the cathode and attached
Perhaps the method of changing the cathode shape and attaching the cathode can solve this problem, which needs further research.