Pt particles in glass

Pt has a very good high temperature performance, 1700 ℃ above the melting temperature, difficult to be oxidized under high temperature, high density advantages, in the production of high quality glass only Pt was used to avoid erosion of the remaining material into a high temperature glass impurities. But the high temperature of the substance also exist loose surface, evaporation and oxidation conditions, the use of Pt crucibles optical glass components inevitably contained Pt.
Pt generally occurs in the glass, principally temperature related, but some use in the pool electrode heating furnace,(OLED modules) glass bubbler --- Pt apparatus, mixer, etc., there will be an instant electrode reaction, resulting in Pt large number of fine glass particles.
Pt particles produced by high-temperature
Studies have shown that, Pt evaporation losses at high temperatures caused largely by PtO2.
Pt when heated in air, leaving an oxide greatly increased loss of Pt, experiments show that heating at lower temperatures, Pt surface no obvious changes. But actually generate a very thin film solid oxide, the oxide film is thickened with the rise of temperature. Heating was continued to a critical temperature, the Pt speaking, this temperature is about 400 ~ 500 ℃, no further thickening of the oxide film, but completely disappeared. That is, in this temperature undergoes a phase change - directly into the gaseous state from solid to PtO2 PtO2, and with the temperature, the more dramatic changes, the generated gases PtO2 more. Trend of gaseous PtO2 depends PtO2 freedom escape from the metal surface, in other words, if the metal surface is open, but also as the power flowing air, then the generated PtO2 was dispersed into the air, and the formation PtO2 strong evaporation. However, if the heated refractory metal surface and the like is closed, and no flow of air as the driving force,(color lcd display module) PtO2 equilibrium partial pressure of gas will be reduced, a small space is formed in supersaturated PtO2. At this time, if the temperature of the refractory metal surface and is still above 500 ℃, gaseous PtO2 can not deposited in solid PtO2 (because it is still being above the critical temperature), but the dissociation into metal Pt deposited in PtO2 the gas phase in equilibrium.

(1) is deposited on the glass surface of the Pt is dissolved in the molten glass, if the glass of the supersaturation Pt, Pt in the form of the glass with metal precipitates form harmful Pt --- "flash." Thus, we can see the "flash" appears, and the Pt crucible temperature, atmosphere, surface protection, and Pt is the solubility of the glass.