真空碳热还原直接制备铁/碳化钛复合粉体和陶瓷
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TF450

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中国科协青年人才托举工程项目(2015QNRC001)。


Direct preparation of Fe-TiC composite powders and its ceramics by vacuum carbothermal reduction
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    摘要:

    传统生产碳化钛系钢结硬质合金的方法是将金属钢粉和TiC粉机械混合后压块烧结成型。该方法原料成本高,且TiC粉表面极易氧化,使得后续的粉末冶金过程中TiC表面与Fe的接触变差,不能紧密黏结在一起,严重影响最终产物的材料性能和纯度。实验采用TiO2粉、石墨粉和还原铁粉作为原料,通过真空碳热还原直接制备出Fe-TiC复合粉体,作为生产TiC系钢结硬质合金的原料。该方法成功避免了TiC粉表面氧化的问题,且原料成本低,产品纯度高,制得的陶瓷性能优良。研究发现,随着原料中碳配比的增加,最终得到的陶瓷产物硬度逐渐降低,而其弯曲强度先升高后降低。同时发现使用Ti粉作为烧结添加剂有助于增强产品的硬度及弯曲强度。最终产品的硬度为1 191.7 HV(11.7 GPa),弯曲强度为1 776 MPa;其制备工艺为:原料配比TiO2:C:Fe=20:8.6:15,温度1 400℃,烧结时长6 h,并加入质量分数为1%的Ti粉作为添加剂。

    Abstract:

    In traditional route to produce TiC-type steel-bonded carbides, steel powder and TiC powder are mixed mechanically and sintered after pressing. The cost of the raw materials in this method is high, and the surface of TiC powder is easily oxidized which makes the wettability between TiC and Fe terrible in following powder metallurgy process. The terrible wettability makes it difficult for Fe to combine tightly with TiC, seriously affecting the properties and purity of the product. The present experiment uses titanium dioxide powder, graphite powder and reduced iron powder to produce Fe-TiC composite powder by vacuum carbothermal reduction firstly, and then the composite powder is used to produce TiC-type steel-bonded carbides. This route successfully avoids the surface oxidation of TiC powder and has the advantages of low cost of materials, high purity of the products and excellent properties of the prepared ceramics. The results indicate that, with the increase of carbon ratio in the raw materials, the hardness of the product decreases while the bending strength increases firstly and then decreases. Besides, the addition of Ti powder enhances the hardness and bending strength of products. The optimal product with a hardness of 11.7 GPa and a bending strength of 1 776 MPa is obtained when the raw material ratio TiO2:C:Fe is 20:8.6:15, temperature is 1 400℃ and holding time is 6 h with Ti powder of a mass fraction of 1% as the additive.

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吴柯汉,张国华,周国治.真空碳热还原直接制备铁/碳化钛复合粉体和陶瓷[J].重庆大学学报,2019,42(4):49-55.

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  • 收稿日期:2019-01-14
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  • 在线发布日期: 2019-04-23
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