Book Description

A summary is presented of a research program aimed at the improvement of high-temperature strain gages of the electrical resistance type. Potential ceramic and metal components were evaluated and a gage was devised that was based on these evaluations. This gage (NBS 5B) was flexible and easy to install; however, it lacked resistance stability at higher temperatures. In an attempt to minimize this deficiency, ceramic cements were developed that showed greater electrical resistivity than had been previously observed in the range 800 to 1800 degrees Fahrenheit; also, a technique was devised for increasing the resistance to ground by applying a fired-on ceramic coating to the grid of a specifically developed unbacked gage. A study was made of the cause of the erratic response of cemented gages that had not been preheated prior to use. There were strong indications that the erratic response was caused mostly by the rapid decrease in resistance that accompanied structural changes in the cement.