Sintering Behavior and Properties of Mo-Cu Composites

Aokui Sun,Yuejun Liu,Dezhi Wang,Zhihua Zhou

doi:10.1155/2018/8703986

Abstract

A simple microwave-assisted aqueous solution strategy combined with a subsequent low-temperature hydrogen reduction process was used to prepare Mo-Cu nanopowders. In order to systematically investigate the densification behavior and properties of Mo-Cu composites, the densification, microstructure, hardness, electrical conductivity, thermal conductivity, and bending strength of Mo-Cu compacts were tested after sintering at different temperatures. Results show that the sintering temperature is a critical factor in the densification process of Mo-Cu composites. The shrinkage rate, density, and hardness of sintered composites increase as the temperature rises. However, too high sintering temperature resulted in the decrease in electrical conductivity (EC), thermal conductivity (TC), and bending strength. By optimizing all the performance indicators, high-performance Mo-25 wt.% Cu composites with a homogeneous microstructure accompanied with good physical and mechanical properties could be successfully obtained by sintering for 2 h at 1200°C.

Highlights

IntroductionOwing to the outstanding physical and mechanical properties (e.g., satisfactory electrical and thermal conductivity, low and adjustable coefficient of thermal expansion, wear resistance, and high temperature strength) of Mo-Cu composites with different copper contents, they are broadly used for the heavy duty service contacts [1]
Owing to the outstanding physical and mechanical properties of Mo-Cu composites with different copper contents, they are broadly used for the heavy duty service contacts [1]
Excessive ammonia solution was instilled into the salt solution till no precipitate and gel left. is obtained solution was heated in a microwave oven to evaporate all liquid, and the dry precipitates were collected and reduced at 650°C for 2 h to obtain Mo-Cu composite powders. e as-prepared Mo-Cu composite powders were compacted in a steel die under the pressure of 250 MPa to produce green parts. e compacts were sintered at 900∼1300°C under reducing atmosphere of Ar-20 vol.% H2 in a tube-type resistance furnace for 2 hours, and the heating rate is 10 ± 6%°C·min−1. en, the sintered samples were cooled to the room temperature (20°C) through free cooling

Summary

Introduction

Owing to the outstanding physical and mechanical properties (e.g., satisfactory electrical and thermal conductivity, low and adjustable coefficient of thermal expansion, wear resistance, and high temperature strength) of Mo-Cu composites with different copper contents, they are broadly used for the heavy duty service contacts [1]. In the last few years, a chemical-activated sintering process has been conducted to improve the sinterability by adding a certain amount of the metal activator into Mo-Cu powders. These activators (such as Co, Ni, or Fe) exhibit a passive effect on the electrical and thermal properties of the M-Cu composites (M W, Mo) [4,5,6,7]. The quantity and content of published works in this area do not seem sufficient to draw a plausible conclusion about successfully preparing Mo-Cu powders with good sinterability and Mo-Cu composite compacts with excellent performance

Methods

Results

Conclusion