| Accession number;07A0043261 |
| Title;DEGRADATION DIAGNOSTICS OF ENGINEERING MATERIALS BY MEASUREMENT OF THERMOPHYSICAL PROPERTIES-RELATIONSHIP BETWEEN OCCURRENCE OF MICRO-CRACKS AND DEGRADATION OF THERMAL CONDUCTIVITY- |
| Author;KATO KAZUNORI(Yamagata Univ., Graduate School, JPN) TAKAHASHI ICHIRO(Yamagata Univ., Fac. Engineering, JPN) |
Journal Title;Thermophys Prop
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Journal Code:X0031A
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ISSN:0911-1743
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VOL.27th;NO.;PAGE.176-178(2006)
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| Figure&Table&Reference;FIG.8, REF.5 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;This paper describes a technique using a thermophysical tester to inspect degradation of engineering materials nondestructively. Influence of uniformly distributed micro-cracks upon its thermal conductivity has been discussed by Hasselman. Incipient micro-cracks are likely to grow within the surface layer of materials. Recently developed thermophysical handy tester is applied to detect such local degradation of thermal conductivity. The tester can measure thermophysical properties in the vicinity of a contacting point on the tested material. Theoretical analysis of heat flow in the layer with micro-cracks can be done to evaluate a thermal resistance caused by micro-cracks in the layer. From the results of the thermal resistance, the thermal conductivity of the layer can be estimated. Fatigue tests are also done experimentally to ascertain this theoretical simulation. Measurements of thermophysical properties and inspections of the surface of specimens before and after fatigue tests are performed by comparison with each other. From the inspection of the specimens of S45C after the tensile-compression fatigue test, dislocations accumulating at grain boundary as well as micro-cracks seem to be the cause of lower thermal conductivity. As a result, it is possible to apply this technique to nondestructive diagnostics for materials which have casehardening such as nitriding SACM645. (author abst.) |
