Date of Award

Summer 2005

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Rice, James

Second Advisor

Domblesky, Joseph

Third Advisor

Nigro, Nicholas

Abstract

The relationship between micro-hardness testing and local density percentages in compacted powder metal green parts was studied in this research. Specimens were studied utilizing image analysis software to produce local density percentages, and microhardness testing to investigate what relationship, if any, exists between the two. SimplePCI image analysis software was used to determine density percentages within a set region of interest. Micro-hardness testing was then performed in that same region of interest and a relationship was developed. The experimental procedures pertaining to SimplePCI image analysis software and micro-hardness testing are described in detail within this thesis. Through investigation of this relationship three objectives were sought as follows. 1. Determination of specimen mounting media (epoxy) 2. Creation of spatial coordinate functions for predicting local density percent and micro-hardness 3. Development of function relating local density percent and micro-hardness The first objective pertained to the viscous epoxy used in mounting PIM green parts. An in depth procedure including mounting, grinding, and polishing of PIM green parts is detailed. Three separate epoxy and hardener combinations and in tum curing environments were studied. Each epoxy was used to determine percent density via optical technique and micro-hardness for defined regions of interest. The relationships between the two were then examined for each of the epoxies and a best fit correlation was determined. Continuing with the epoxy that produced the best relationship between optical density determination and hardness for the same region of interest, spatial coordinate functions were then developed to predict local density and micro-hardness at any point in the region. Empirical data was collected for local density and micro-hardness over a specified mesh of the cross-section. From this density and hardness data, spatial coordinate functions were developed. These functions allowed mapping of the entire cross-section; however, it was limited to the bounds of the empirical data collected. After collecting density and hardness data throughout the specified mesh a linear relationship was observed between density percent and micro-hardness. The relationship is as follows: Percent Density= 1.18 * Micro-Hardness- - 5.41 "Micro-hardness in terms of kg/mm2 The conditions used in formulating this relationship are specific to the material and test methods examined in this thesis. The linearity is only valid over the range tested. With these material and test specific conditions, the linear relationship has a correlation coefficient of 98.1 %, clearly showing that a linear relationship does exist between microhardness and local density percentages. With some proposed future work, these findings will prove very useful and will be advantageous to anyone working in the P/M industry.

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