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

这个小企业创新研究的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铁在工业上得到了广泛的应用。它们是由铁粉与Fe2P或Fe3P粉混合而成。在烧结过程中，在1056摄氏度（1950华氏度）时出现液相，使磷扩散到铁中的固溶体中。存在的问题是只有两家粉末生产商销售该产品，并且由于磷铁颗粒的熔化，烧结部分可能会留下较大的孔隙。为了在烧结前把磷涂在铁上，曾作过几次尝试。(1)第一次尝试是将P205加入甲醇中，喷在铁粉上。试验失败了，因为磷没有减少氧化物或水雾化粉末，可能提供了额外的氧化物作为屏障。将磷化氢引入铁粉加热床，进行了第二系列试验。虽然磁性和拉伸性能得到了显著改善，但磷化氢价格昂贵，安全预防措施使其无法使用。红磷不是安全问题。如果将氢引入到加热的铁粉中，它将减少表面氧化物。然后，一个干净的表面就可以接受磷涂层，并且可以便宜地覆盖颗粒，而且没有安全问题。人们相信，这一过程也会使性能得到同样的改善。如果这个过程是成功的，提议者将考虑建设一个工厂提供包覆磷铁粉用于商业用途。还将考虑该过程的许可问题。这种粉末的市场已经形成。粉末冶金磷铁部件目前广泛应用于现代汽车的喷油器和传感器中。它们也广泛用于继电器，螺线管和其他磁性设备。将涂覆的磷铁粉末引入市场将导致更有效、更可靠的磁性设备，这些设备将更轻或更节能。

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.