SBIR Phase I: Improvement in Magnetic and Tensile Properties by Coating Iron Powder with Phosphorus

这个小企业创新研究第一阶段项目应该改善使用粉末冶金工艺制造的磷铁零件的磁性和拉伸性能。采用粉末冶金技术制备的磷铸铁在工业上有着广泛的应用。它们是通过将铁粉与Fe2P或Fe3P粉末混合而配制的。在烧结过程中，在1056 oC（1950 oF）下出现液相，将磷扩散到铁中的固溶体中。存在的问题是，只有两个粉末生产商销售该产品，并且由于磷铁颗粒的熔化，大的孔隙可能保留在烧结部件中。 已经进行了几次尝试以在烧结之前将磷涂覆在铁上。(l)第一次尝试是将P205添加到甲醇中并将其喷洒在铁粉上。试验失败，因为磷不能还原氧化物或水雾化粉末，可能提供了额外的氧化物作为屏障。第二系列试验是通过将磷化氢引入铁粉的加热床中进行的。虽然磁性和拉伸性能得到了显着改善，但膦是昂贵的，安全预防措施排除了它的使用。 赤磷不是安全问题。如果将氢气引入加热的铁粉中，它将还原表面氧化物。然后，可以获得清洁的表面来接受磷涂层，并且可以廉价地涂覆颗粒并且没有安全问题。据信，该方法将导致相同的性能改进。 如果工艺成功，提议者将考虑建造一个工厂，提供商业用途的包覆磷铁粉。还将考虑对该工艺发放许可证。这种粉末的市场已经建立。粉末冶金磷铁零件目前广泛用于汽车喷油器和传感器。它们还广泛用于继电器、继电器和其他磁性装置。将涂覆的磷铁粉引入市场将导致更有效、更可靠的磁性装置，其将更轻或更节能。

This Small Business Innovation Research Phase I project should improve the magnetic and tensile properties of phosphorus iron parts fabricated using the P/M process. The phosphorus irons fabricated using P/M technology are being widely used in industry today. They are formulated by admixing iron powder with Fe2P or Fe3P powder. During sintering, a liquid phase occurs at 1056oC (1950oF) which diffuses the phosphorus into solid solution in the iron. Problems exist in that only two powder producers sell the product, and large pores can remain in the sintered part, owing to the melting of the ferrophosphorus particles. Several attempts have been made to coat the phosphorus on the iron prior to sintering.(l) The first attempt was to add P205 to methanol and spray it on the iron powder. The trial resulted in failure because the phosphorus did not reduce the oxide or the water atomized powder, and perhaps provided additional oxide which acted as a barrier. A second series of tests were made by introducing phosphine to the heated bed of iron powder. Although magnetic and tensile properties were significantly improved, phosphine is expensive, and safety precautions preclude its use. Red phosphorus is not a safety problem. If hydrogen is introduced to the heated iron powder, it will reduce the surface oxide. A clean surface would then be available to accept the phosphorus coating, and the particles could be coated inexpensively and with no safety concerns. It is believed that the same improvement in properties would result from this process. If the process is successful, the proposer would consider construction of a plant to furnish coated phosphorus iron powder for commercial usage. Licensing of the process would also be considered. A market for the powder is already established. P/M phosphorus iron parts are currently widely used in fuel injectors and sensors in present day automobiles. They are also widely used for relays, solenoids and other magnetic devices. The introduction of a coated phosphorus iron powder to the marketplace would result in more efficient, reliable magnetic devices that would be lighter or more power efficient.