Thermoelectric Method of Plastic Deformation Detection

The paper presents an approach of non-destructive testing of plastic deformation of metals and alloys by measuring the differential thermoelectric power. Using the developed measuring device for this purpose, measurements of thermoelectric power were performed on several types of steels that are used in the manufacture of product pipelines. Incisions were made on the surface of the testes objects, for the purpose of experimental detection of the place of plastic deformation. In the process of stretching, thermoelectric power was measured at and near the place of the proposed plastic deformation. During the process of stretching the sample, the decrease in thermoelectric power measurement occurs almost linearly. The maximum change in the thermoelectric power measurement of the tested object was observe before the rapture discontinuity.

Dental Alloy Sorting By the Thermoelectric Method

ABSTRACTObjectives: A nondestructive, rapid, and practical method of dental alloy sorting is desirable. In this study, the hypothesis to be tested is that dental alloys show significantly different and high thermoelectric power values, on the basis of which alloy sorting is possible.Methods: Six silver-colored commercial dental casting alloys are used in this study: two silver alloys, one gold-silver-palladium alloy, one cobalt-chromium alloy, one nickel-chromium alloy, and one titanium alloy. The thermoelectric power of their castings was determined against constantan using a simple apparatus developed in a previous study. Linear least square fitting was applied to the measured thermal-EMF-temperature curve to determine the thermoelectric power for the temperature ranges of 298.303 K (temperature difference Δt = 5 K), 298.308 K (Δt=10 K), 298.313 K (Δt=15 K), and 298.318 K (Δt=20 K). The results were analyzed using one-way ANOVA and by the Scheffefs test at a significance level of α=0.01.Results: When the temperature difference was 10 K or less, the difference in the thermoelectric powers of the alloys was not always statistically significant. However, when the temperature difference was 15 K or more, the thermoelectric powers of the six alloys differed significantly.Conclusions: The results indicated the feasibility of rapid sorting of specific dental alloys by the thermoelectric method, provided a sufficiently large temperature difference is achieved. (Eur J Dent 2010;4:66-70)