Before, platinum-rhodium alloy is a precious rare metal, the reserves have been found in China is very low, with the rapid development of a series of glass industry such as quartz fiber production, especially the development of a series of new boron nitride fiber, zirconia fiber and other special fiber industry, its application is constantly multiplying. Reduce the natural loss of platinum in daily production operations and high temperature oxygen volatilization loss, not only can save high cost for enterprises, but also can realize the full use and protection of non-renewable resources for the country. The common operating temperature of platinum-rhodium alloy wire drawing crucible is between 1000°C and 1150°C. The platinum on the outer surface of the crucible is at room temperature. Contact with oxygen in the air is oxidized to generate Pt02. When heated to 450°C in an oxidizing atmosphere, Pt02 on the surface of the crucible volatilizes into vapor phase Pt02, which decomposes into Pt and 0.2 when above 550°C. Decomposed Pt deposited on the solid surface or escaped in the air, resulting in loss of platinum; Rhodium is chemically similar to platinum at high temperatures. In the atmosphere, rhodium is oxidized to PH203 at about 600°C and becomes vaporized at about 950°C. It can be seen that under the common high temperature conditions of daily production operations, the loss of platinum will increase with the increase of use time.
In terms of reducing the loss of the use of platinum crucible, the existing Chinese patent application CN101967313A disclosed "a protective coating to inhibit the oxidation and volatilization of platinum leakage plate" in the pretreatment process of platinum leakage plate still needs to be ground and coarsed on the painted part, which shows that the adhesion of the coating is not very high. Moreover, the grinding and coarsening of the platinum plate surface will inevitably cause the loss of molybdenum alloy.
A kind of oxidation protective coating and its preparation method for platinum wire drawing crucible are proposed, which can effectively reduce the loss of platinum in long term, reduce the loss of precious metals, minimize the deformation of platinum wire drawing crucible, and inhibit the oxidation and volatilization of platinum wire drawing crucible surface under high temperature condition.
