Chemical Reduction Preparation Of Copper Coated Iron Powder Process And Properties

Coating powder is a new type of coating and powder metallurgy material. Due to its great varieties and special performance, it has been widely used in the industries including defense industry, mechanical manufacture, chemical industry and other fields. In the microscopic view, the coating powder features in multi-phase, coated integrality and the characteristics of its various components can be shown according to it's diferent need;In the macroscopic view, coating powder is character by its homogeneous property, which realizes uniform metallic phase fabric of products, and meanwhile greatly reduces or eliminates the defects of unstable performance and non-homogeneous components of products caused by non-uniform blending.This article introduces the coated powder, and the basic principles of electroless copper plating, summarizes the current status of copper coated iron powder preparation technology, and makes copper coated iron powder which have good performance such as outward appearance, apparent density and so on, The pretreatment technics, copperr-plating technics, post-processing technics and the properties of copper coated iron powder are researched. The mechanism of electroless alkaline-based plating copper is initially assessed.The conclusion can obtain as follow:1. Pretreatment is the success or failure key of copper-plating, the copper-plating will achieve the best result after adopting the acid pickling -- alkali wash two steps processes.2. The chelating agent is the determinant factor which can help achieve the aim that electroless plating copper in alkaline-based system. Chelating agent D and copper can form a stable complex, and eventually we get better copper-coated iron powder. Bath of pH value impact the color of copper coated iron powder and the speed of electroless copper plating. In this paper, sub-volume of.added sodium hydroxide to maintain the value which electroness copper plating required. The reductant concentration,plating solution temperature and main salt concentration have a great influence on the speed of aggradation and the colour of copper coated iron powder.Then it affects the apparent density and particle size distribution.The intensity of mechanical agitation have a little influence on performance of copper coated iron powders.3. The better electroless copper-plating conditions is: The concentration of reducing agent is 25ml/L; the concentration of chelating agent potassium tartrate is 100g/L; the chelating agent of dispersing agent is 0.03 g/L; the concentration of major salt is 33g/L; the plating solution temperature is 45℃; the radio of liquid-to-solid is 30; the intensity of mechanical agitation is 300-500r/min;The pH value is 12～13; the number of adding sodium hydroxide is 4-5times.4. The passivation process of copper coated iron powder showed that:the Synergy of BTA and Surfactants A passivates better,the volume of BTA is 6 g/L,the volume of Surfactants A is 4 g/L. The Passivation temperature is 50-55℃;The Processing time is 3 minutes.5. The study on the performance of copper coated iron powder indicates:The copper powder has the great influence on the apparent density.The copper concentration of copper coated iron powders has a great influence on its color and granularity. The measurement to the oxidative resistance ability indicates that copper coated iron powder containing 20wt% copper has better oxidized ability at normal temperature; The surface topography indicates: The surface of iron powder is smoothing and the surface of copper coated is roughness.It appares granular copper crystals and it is about 447nm.