Thermophysical properties of roll-compacted nickel sheet for high-density infrared sheet fabrication
- PDF / 874,792 Bytes
- 12 Pages / 606.24 x 786 pts Page_size
- 32 Downloads / 141 Views
11/7/03
12:15 PM
Page 3043
Thermophysical Properties of Roll-Compacted Nickel Sheet for High-Density Infrared Sheet Fabrication J.D.K. RIVARD, A.S. SABAU, C.A. BLUE, E.K. OHRINER, and N. JAYARAMAN This work is focused on the analysis of the high-density infrared (HDI) sheet fabrication process of powder compacts. Measurements of material properties and distribution of incident heat flux on processed powder sheet surfaces have been conducted with the aim of obtaining a complete set of data that can be used as input in computer simulation software. It was found that these materials exhibit significant anisotropy in thermal conductivity. Indirect measurements indicate that there are small variations in density across the thickness of the powder compacts. Temperature data were obtained from thermocouples placed on the backside of the sheet. The evolution of thermal profile during a static pulse was investigated by using a three-dimensional finite volume model. Numerical simulation results are very sensitive to the surface emissivity. Numerical simulation results agree very well with experimental results for the case in which no liquid pool was formed during HDI processing.
I. INTRODUCTION
INTERMETALLIC and refractory metals are inherently difficult to process into sheet due to their thermomechanical properties. A new process developed at the Infrared Processing Center at the Oak Ridge National Laboratory has shown much promise in significantly reducing the time and cost in producing these attractive engineering materials. This process employs a plasma arc lamp to rapidly heat and liquidphase-sinter powder metal precursors into near-net-shape sheet.[1] The process variables include lamp power, lamp scanning speed, and lamp power distribution. The lamp power and lamp scanning speed can be varied with time. In order to control the process and prescribe the process variables that are appropriate for a particular application, the evolution of temperature and resulting liquid pool shapes that form during this process must be understood. Due to the high power densities used in the high-density infrared (HDI) processing, substantial sintering can take place in seconds. This work is focused on the analysis of the HDI process for powder compacted materials. The sheet precursor considered for this study is a Ni powder compact material. The development was conducted only for this material, but the methodology presented is in general applicable to any other powder compacted material. In Section II, a brief description is presented on the manufacturing process for the sheet precursor and micrographs of sheet microstructure have been presented. In Section III, a complete set of thermophysical property data is presented that can be used as input in computer simulation software. The experimental setup for HDI processing is described in Section IV–A. Additional data on sheet fabrication using HDI processing can be found in Rivard et al.[2] In Section IV–B, J.D.K. RIVARD, Ph.D. Candidate, Chemical and Materials Eng. Department, Univ
Data Loading...
