DEVELOPMENT OF METHODS AND INSTRUMENTS FOR MECHANICAL EVALUATION OF REFRACTORY MATERIALS AT VERY HIGH TEMPERATURES

A mechanical-testing system was established which is capable of providing tensile and compressive stress-strain data and shear-strength data up to 4000 deg F in vacuum. The results of an evaluation of the system using a molybdenum0.5% titanium alloy in the bar form are presented. Tension, compression, shear, and bearing tests were conducted at temperatures up to 3500#DEF. A detailed description of the testing system and specimen designs is presented. An optical strain-measurement system which permits displacements to be measured directly in the gage section is described. With the objective of developing equipment and techniques for use to 6000 deg F or higher, problems to be solved in order that accurate data will be obtained are considered. Recommendations are made concerning furnace design, temperature and strain measurement, and specimen, grip, and loading design. In particular, the probable advantages of graphite heaters coated with tantalum carbide are pointed out; plans for experimental investigations and a description of apparatus built to study carbide coatings are presented. The further investigation of two-color pyrometry was also recommended. (auth)