A new surface modification technique, called “iron-powder pack (IPP) treatment”, has been proposed. During IPP treatment, carbon and nitrogen diffuse into a metal substrate by treating it with a mixture of iron and carbon powders at high temperature in a nitrogen flow. This paper describes the effects of adding alumina to the mixture of iron and graphite powders on the microstructures and hardness of SUS430 ferritic stainless steel after IPP treatment. The alumina powder was added to prevent powder mixtures from sintering. A 7:3 (volume ratio) mixture of iron and graphite powders was used as a “base powder”, and the volume ratio of the alumina powder added to the base powder was varied from 0:1 to 50:1. A steel pipe packed with SUS430 steel and powder was heat-treated at 1273 K for 3.6 ks in a nitrogen flow and then rapidly cooled in water. A surface-modified layer formed on the SUS430 steel through IPP treatment. When IPP treatment was performed using only the base powder, carbon was detected in the surface-modified layer. Both carbon and nitrogen diffused when alumina was added to the base powder. However, the thickness of the surface-modified layer gradually decreased from 380 to 125 µm with an increase in the amount of alumina. A similar tendency was observed in the surface hardness of the steel. In addition, the effects of subzero treatment and immersion in an aqueous nitric acid solution on the modified steel are discussed.

已经提出了一种新的表面改性技术，称为“铁粉包装（IPP）处理”。在IPP处理过程中，碳和氮通过在氮气流中在高温下用铁和碳粉的混合物处理而扩散到金属基底中。本文介绍了在铁和石墨粉末混合物中添加氧化铝对IPP处理后SUS430铁素体不锈钢的显微组织和硬度的影响。加入氧化铝粉末以防止粉末混合物烧结。铁和石墨粉末的7：3（体积比）的混合物用作“基础粉末”，并且添加到基础粉末中的氧化铝粉末的体积比在0：1至50：1之间变化。将装有SUS430钢和粉末的钢管在氮气流中于1273 K热处理3.6 ks，然后在水中快速冷却。通过IPP处理在SUS430钢上形成的表面改性层。当仅使用基础粉末进行IPP处理时，在表面改性层中检测到碳。当将氧化铝添加到基础粉末中时，碳和氮均扩散。然而，表面改性层的厚度从380逐渐减小到125μ米与增加的氧化铝的量。在钢的表面硬度中观察到类似的趋势。此外，还讨论了零以下处理和浸入硝酸水溶液对改性钢的影响。