Preparation Technology And Performance Research Of Spherical Powders Used For Metal Injection Molding

On the basis of systematic investigation and analysis of the technical requirements of powders used for MIM and preparation methods of metal powders, this study not only proposes basic ideas and experimental method of oxyhydrogen flame spheroidisation technology, but also design experimental equipment. The research prepares copper powders, nickel powders and titanium powders which are used for MIM, and demonstrates the technical feasibility and scope of application.The core of powders spheroidisation technology and experimental equipment is the uniform feeding technology of the raw powders and spheroidisation technology. In this topic, powders fluidization combined with powders spheroidisation provides a new way for preparation technology of powders used for MIM.This research adopts fluidization technology in order to solve the problem of uniform feeding of the raw powders. The research of powders fluidization shows that when the experimental equipment, use powders sintered plate with pore size of10μm, powders fluidization technology can reach good fluidization quality, and meet the needs of experimental oxyhydrogen flame spheroidisation technology with uniform and continuous.This investigation found that powders spheroidisation processing can be a variety of heating methods to choose, including, the best one is radio frequency plasma, and spheroidisation technology by oxyhydrogen flame can be used to prepare powders with low-cost. This study adopts oxyhydrogen flame spheroidisation technology to treat copper powders, nickel powders and titanium powders respectively. The results show that oxyhydrogen flame as a mode of heating can meet the needs of spheroidisation copper powders, on the contrary, can not meet the requirements of spheroidisation nickel powders (spherical rate less than50%). Titanium is high melting point active metal. The technology of oxyhydrogen flame spheroidisation titanium powders requires further detailed exploration.In this study, experimental raw materials are electrolytic copper powders. Through fluidizaton of powders and spheroidisation of oxyhydrogen flame, we can obtain the spherical powders with high spherical rate, high fluidity, and diameter less than20μm used for MIM, establish an experimental device, and analyze the relevant parameters of powders performances. The results show that in the experiment of oxyhydrogen flame spheroidisation copper powders, the highest spherical rate of copper powders can reach99%, at1.75m3/h the carrier gas flow,9.8g/min powder feeding rate; mass percent of particle size smaller than20μm of product powders reach45%, at2.5m3/h carrier gas flow rate,25.3g/min powder feeding rate. Tap density and liquidity of copper powders respectively is4.25g/cm3and22.85s/50g. After spheroidisation, tap density and liquidity of copper powders have a significant improvement.The results show that spheroidisation technology by oxyhydrogen flame can be used to prepare powders used for MIM with low-cost and higher spherical rate. Plasma technology will become a primary method of preparation metal powders used for MIM in the future.