In N18 alloy sheet production, pickling operation prone to pickling and in pickling control the thickness of the sheet size tolerance phenomenon, conducted a comparative test study the concentration of hydrofluoric acid, nitric acid concentration and pickling temperature pickling effect on the N18 plates, and the plates were sampled after pickling hydrogen content analysis. the results showed that the pickling solution of hydrofluoric acid corrosion plays a major role when the concentration of about 8%, the pickling reaction more gentle, pickling temperature rises slowly, good plate pickling effect; pickling solution temperature had a significant effect on the pickling rate, in order to ensure the pickling process control, pickling reaction temperature should be controlled at ≤40 ℃; nitrate control action reaction rate and the hydrogen content, increases the concentration of nitric acid, the pickling reaction rate, suitably 40% to 50% nitric acid.

Evaluation of different relationships and bond strength of ceramic brackets after over three kinds of surface treatment methods ceramic restoration specimen. Methods: cobalt-chromium porcelain, cast porcelain, ceramic and polymeric zirconium porcelain category 4 specimens after sandblasting (SB), hydrofluoric acid etching (HFA), sandblasting + etching (SB + HFA) coated on the surface treatment silane coupling agent (SCA), and then bonding ceramic brackets by 37 ℃ water bath for 24h detect bond strength (SBS), scanning electron microscopy bracket bonding front prosthesis surface roughness and surface removal prosthesis adhesive residue situation. Results: cobalt-chromium porcelain, cast porcelain ceramic and polymeric shear strength specimens were statistically significant (P0.05) and zirconium porcelain specimen difference; shear strength cobalt chromium porcelain and cast porcelain specimen the difference was not statistically significant. Scanning electron microscopy showed that the surface roughness of the specimen 4 groups has increased significantly. The roughness of the sandblasted group and sandblasting + etching group was significantly higher than the specimen surface etching treatment group; surface treatment effect blasting and sandblasting + etching groups is insignificant, sandblasting group Class 4 test pieces surface adhesive residue least. CONCLUSION: The three surface treatment methods can meet the needs of clinical orthodontics. On the surface of the specimen after the removal of the minimum set of brackets sandblasting, sandblasting combined with acid etching does not significantly increase the shear strength.