Selectron of Materials for Use at Temperatures Above 1500 deg C in Oxidizing Atmospheres

摘要

The purpose of this work was to select materials for applications in oxidizing atmospheres at temperatures of a minimum of 1500 deg C. Several requirements had to be fulfilled, e.g. long-term oxidation resistance, low vapour pressure, creep resistance and low gas permeability. Another important point was to avoid reactions and sintering in material combinations with silica forming materials. The investigation was based on a detailed literature screeening, followed by compatibility tests at 1600 deg C in air with potential materials (Al_2O_3, ZrO_2, CeO_2, La_2O_3, Y_2O_3, HfO_2, MgO centre dot Al_2O_3) and MoSi_2 as an example of a silica-forming material. The result of these experiments was, that only Y_2O_3 and HfO_2 did not show severe reactions in contact with MoSi_2. Since most of the materials available did not fulfill all the requirements, some new materials were investigated: CIPed MoSi_2 with different additives (SiC, ZrB_2) and recrystallized SiC (RSiC) with a polymer (polysiloxane) derived MoSi_2-field coating. The oxidation behaviour of these materials was evaluated by continuous thermogravimetric measurements at 1500 deg C over a period of 100 h in air and by detailed postexperimental investigations.