Post Treatment Process and Selective Laser Sintering Mechanism of Polymer-Coated Mo Powder

Bin Liu,Yuxin Li,Peikang Bai

doi:10.2174/1874088x01105010194

Abstract

A novel preparing method of polymer-coated molybdenum powder was presented. A type of multi-component polymer-coated molybdenum powder was chosen for selective laser sintering. The effect of the process parameters on the part's characteristics is investigated. Based on our study for dynamic laser sintering process of polymer-coated molybdenum powder, its laser sintering mechanism was reported as follows: at the early stage of laser sintering, the viscous flow is the major mechanism; during the laser sintering, the melting/solidification is the major mechanism. Furthermore, a model corresponding to the mechanism was discussed schematically, which could be used to explain the material migrating mode during laser sintering process. The laser sintering experiments of polymer-coated Mo powder was conducted in the self-developed laser sintering machine, and optimized parameters have been acquired. At last, the post treatment process of laser sintered parts has been developed and refractory metal parts of Mo/Cu composites are gained. The post treatment process includes debinding, high temperature sintering and melting infiltration, which is sintering framework-Mo by high temperature combining with Cu impregnation method. It is found that the mechanical properties of parts have been greatly improved after the post treatment process.

Highlights

Nowadays, Consolidation of loose powder by local laser heating is becoming a promising manufacturing technique because of the easy control over both powder deposition and laser radiation
SLS/SLM technologies are widely used in various industries, medicine and research offering a range of advantages compared to conventional manufacturing techniques: shorter time to market, use of inexpensive materials, higher production rate, versatility, high part accuracy, ability to produce more functionality in the parts with unique design and intrinsic engineered features [3]
The essential operation is the laser beam scanning over the surface of a thin powder layer previously deposited on a substrate

Summary

Introduction

Consolidation of loose powder by local laser heating is becoming a promising manufacturing technique because of the easy control over both powder deposition and laser radiation. Selective laser sintering/melting (SLS/SLM) technology makes it possible to create fully functional parts directly from metals, ceramics, plastics without using any intermediate binders or any additional processing steps after the laser sintering operation [1,2]. The essential operation is the laser beam scanning over the surface of a thin powder layer previously deposited on a substrate. The powder layer thickness, the energy density and the diameter of the laser beam and the Molybdenum is widely used as refractory material. During selective laser sintering of polymer-coated molybdenum powder, the polymer plays the role as binder, which can bind the molybdenum particle and form the prototype. Binding is caused by laser induced localized heating, and the duration of the laser beam at any powder particle is short, typically between 0.5 and 25ms. For laser sintering of plastics, two mechanisms are put forward: viscous flow when the powder has appropriate temperaturedependent viscosity, and melting, as reported by Scherer [8] and Gusarov et al [9] the study on laser sintering mechanism of polymer-coated metallic powder was seldom reported, especially for the polymer-coated molybdenum powder [10,11,12]

Objectives

Methods

Results