The binder composition POM (polyformaldehyde) in the injection molded 17-4PH stainless steel body was catalytically degreased under nitric acid atmosphere, and then thermal degreasing and sintering were carried out in a vacuum sintering furnace. The effects of powder loading and catalytic degreasing time on the catalytic degreasing rate were studied, and the effects of powder loading on the microstructure, density and tensile strength of sintered products were also studied. The results show that the microstructure of the sintered products is composed of austenite and a small amount of ferrite. With increasing the powder loading from 55.1% to 65.7%, the catalytic degreasing rate of the sintered sample decreases from 7.8% to 5.2%; the density increases from 7.56 g/cm3to 7.66 g/cm3, and the tensile strength increases from 1 076 MPa to 1 204 MPa. With increasing the thermal retention time from 30 min to 90 min at 130 ℃, the catalytic degreasing rate increases from 4.9% to 6.7%. When the thermal retention time in the range of 90?150 min, the catalytic degreasing rate stabilise at about 6.7%. With the powder loading of 65.7%, the POM in the binder can be completely removed by 90min catalytic degreasing. The degreasing rate reaches 87%, and the injection blank forms a complete communicating channel.%在硝酸气氛下对注射成形17-4PH不锈钢坯体中的粘结剂成分POM(polyformaldehyde, 聚甲醛)进行催化脱脂,然后在真空烧结炉中进行热脱脂和烧结,研究粉末装载量和催化脱脂时间对催化脱脂率的影响,以及粉末装载量对烧结不锈钢的显微组织、致密度与抗拉强度的影响.结果表明:烧结不锈钢的显微组织为以奥氏体为主和少量铁素体共同组成的复合组织.随粉末装载量从55.1%增加至65.7%,催化脱脂率从7.8%降低到5.2%,但烧结密度从7.56 g/cm3增加到7.66 g/cm3,烧结不锈钢的抗拉强度从1076 MPa提高到1204 MPa;130 ℃下随催化脱脂保温时间从30延长至90 min,催化脱脂率从4.9%增加至6.7%,在90～150 min时间段内催化脱脂率稳定在6.7%左右.粉末装载量为65.7%的注射喂料经过90 min催化脱脂,可完全脱除粘结剂中的POM,催化脱脂率达到6.72%,注射坯形成完整的连通孔道.
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