Power Research

Malur N. Srinivasan ¹, Robert J. Bennett ², Don E. Bray ²

Affiliations
1 Professor of Mechanical Engineering, Lamar University, Beaumont, Texas, USA, US
2 Department of Mechanical Engineering ,Texas A&M University, College Station, Texas 777843, US

Abstract

The results of an investigation conducted to study the relation of critically refracted longitudinal wave (L_CR) velocity with graphite nodularity and matrix in ductile iron are reported in this paper. The relation between L_CR velocity and graphite nodularity was studied using as-cast test bars obtained from one foundry. Three groups of test bars of similar nodularity obtained from a second foundry were subjected to heat treatment so as to obtain ferritic matrix in the first group, martensitic matrix in the second and tempered martensitic in the third, to enable the relation of L_CR wave velocity with these matrices to be studied. Also three other test bars from the second foundry were subjected to annealing, normalizing and quenching and grouped with an as cast test bar of similar range of nodularity, to evaluate the residual stress developed in each case. The approach followed in this investigation enabled qualitative assessment of the effects of graphite nodularity, matrix and residual stress on the L_CR velocity in ductile iron.

Keywords

Graphite Nodularity, Critically Refracted Longitudinal Wave, Residual Stresses, Ductile Iron

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Malur N. Srinivasan ¹

Affiliations
1 Department of Mechanical Engineering Lamar University Beaumont, Texas - 77710, US

Abstract

This paper deals with the assessment of the potential of nanocrystalline tungsten carbide-cobalt (WCCo), titanium disilicide (TiSi₂) and titanium silicide (Ti₅Si₃) for sliding wear-resistant applications. All the materials were milled in a laboratory attritor and the milled powders were consolidated using equal channel angular extrusion (ECAE) process in three cases and chemical consolidation using polycarbosilane (allylhydridopolycarbosilane-AHPCS) in one case. The microhardness of each consolidated sample was measured using a Vickers hardness tester. The crystallite sizes of WCCo, Ti₅Si₃ and TiSi₂ consolidates after ECAE and Ti5Si3 after attritor milling and prior to chemical consolidation were determined using X-ray diffraction and, the relationship between the crystallite size and microhardness in these cases was examined. The data on microhardness of all the samples was analyzed with reference to current literature to assess the potential of each consolidate for sliding wearresistant applications. The results indicate that attritor-milled Ti₅Si₃ consolidated using polycarbosilane as the binder appears to have the best potential for sliding wear-resistant applications. The experimental data reported in this paper was obtained by former graduate students under the direction of the author at Lamar University.

Keywords

Tungsten carbide, Cobalt, Titanium disilicide, Titanium silicide, Attritor mill, Nanostructure, X-ray diffraction, Microhardness, Sliding wear.

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