A year has passed. 2021 is still full of challenges and unlimited possibilities. No matter what is in front of us, we must use the greatest enthusiasm and the highest morale. The most diligent spirit and the most tenacious will to go all out. In short, today's Xiaomei mainly wants to talk with you about the alternative technology of phosphating, which we are familiar with. After reading the following ceramic treatment technology, it will help us to further understand the role of ceramic and film-forming mechanism.
What is ceramic treatment and what is the principle of ceramic treatment
Metal workpieces usually need pretreatment, including degreasing, derusting and antirust. In addition, it is necessary to form chemical conversion film on the surface of metal workpiece during pretreatment. The conversion film has a certain anti-corrosion ability. It can prevent the parts from re rusting in a short time before spraying, increase the surface roughness of the parts, and enhance the adhesion between the coating and the substrate. The existing processes for the treatment are mainly phosphating process, encapsulation process, surface silylation process and organic film pretreatment process. The existing ceramic process is to immerse the metal workpiece in the ceramic solution containing fluorozirconate or soluble fluorozirconate, and form a corrosion-resistant zirconia film on the surface of the metal workpiece by reaction, so as to realize the passivation of the metal workpiece. Among them, the potting solution is usually acidic, which is prepared by adding water and regulator in the potting agent, and its composition is particularly important for the potting effect of the workpiece.
What is ceramic treatment and what is the principle of ceramic treatment
Mechanism of film formation: sodium fluorozirconate and potassium fluotitanate were hydrolyzed in water to prepare zirconia sol and titanium dioxide. Acid ceramic solution will corrode the surface of metal workpiece and reduce the concentration of H + on the surface of metal workpiece: me Xe → mex +, me represents metal atom, 2h + + 2e → 2 [H]; at the same time, under the catalysis of nano silicon, zirconia reacts with [H]: ZrO2 + 4 [H] → [Zr] + 2H2O, promoting the production of [H] and mex +, resulting in a sharp decrease in concentration. When the concentration of mex + and zrf62 - on the surface of metal workpiece reaches the solubility constant KSP, zirconate precipitation will be formed, which is formed by hydration with water molecules. With [Zr] and titanium dioxide colloidal particles as cores, the film-forming materials attached to the surface of metal workpiece accumulate continuously to form crystal nuclei. Under the action of silane coupling agent and physical accumulation process, the nuclei continue to grow and form grains. The matrix is a ceramic film cross-linked by zirconate and silane, which has improved corrosion resistance and good rust resistance.
Moreover, the concentration of titanium dioxide in the titanium dioxide sol on the surface of metal workpiece is higher than that of [Zr], and the addition of potassium fluotitanate is beneficial to accelerate the accumulation of membrane core and membrane core. Speed up the forming of ceramic membrane.
