废硬质合金回收及再生料工艺优化研究

【作者】 张兴华；

【导师】 汪明朴；

【作者基本信息】 中南大学 ， 材料物理与化学， 2006， 硕士

【摘要】 废旧硬质合金的回收有很多方法，不同方法得到的产品性能有比较大的区别。对回收料性能进行研究，最大限度地发挥钨资源的价值非常重要。本论文对锌溶法回收废旧硬质合金混合料技术以及如何更好地将回收料应用于硬质合金的生产，最大幅度地提高产品的使用价值做了初步的探讨。本文首先研究了锌溶法回收工艺对硬质合金再生混合料质量的影响。在不同的锌加量，不同的锌溶时间等工艺参数下，以及使用不同的锌溶设备时，混合料的出料率和锌残留量等影响混合料质量的因素都会发生明显变化。通过化学分析、光谱分析等方法研究了物料的杂质含量，利用各种粒度分析方法分析了物料的粒度平均大小以及粒度分布情况，利用x-ray方法分析了再生WC的亚晶完整情况。通过寻找不同湿磨时间以及不同的烧结温度下再生料产品硬度、强度、耐磨性变化规律，找到满足不同使用条件的最佳工艺参数。根据使用要求的不同，利用现场使用对比的方法，研究了利用优化的工艺参数生产的拉丝模、钻头、刀片等再生料制品和正常工艺条件下生产的原生料制品的使用性能的差异。研究的重要结果如下：1、通过减少合金块料的大小、采用新式熔炼炉可以提高熔炼效率从而减少碳的损失；为了降低氧的含量或者按照用户的需要控制碳的含量可以加入适当的碳；通过保证熔炼时间、保证加锌量可以降低锌在混合料中的残留量。2、由于再生料是使用过的合金生产出来的，在回收料的生产过程中不可避免会带来杂质，所以再生料中硅、镁、铁、钙、钼、镍等杂质比原生料的相对要高一些。再生料WC的粒度与废合金中晶粒度相比没有多大的差别，粒度分布比原生料更窄一些，其晶型更加完整。在合金晶粒度与湿磨时间关系图上存在一段近似线性的区间，但再生料的线性区间要长一些。3、在24h到72h之间取不同的时间进行湿磨时，随着烧结温度从1370℃升到1450℃时，抗弯强度都有不同幅度的提高；在1370℃到1450℃之间任意烧结温度下，当湿磨时间从24h到72h之间变化时，抗弯强度有不同程度的下降。在24h到72h之间取不同的时间进行湿磨时，随着烧结温度从1370℃升到1450℃时，再生料产品硬度的变化比原生料硬度变化更加有规律，并都有一个下降的趋势存在；同样在1370℃到1450℃之间任意烧结温度下，当湿磨时间从24h到72h之间变化时，硬度有不同程度的提高。再生料变化比原生料更加有规律。随着湿磨时间的延长，硬质合金的耐磨性逐渐提高，但在1390～1430℃之间有一个耐磨性的峰位，并且无论哪一种湿磨时间都有这个特点。和硬度相同，不同的湿磨时间、不同的烧结温度，再生料耐磨性的变化也更加有规律。为了保证产品有较好综合性能，我们一般取强度曲线与硬度曲线的交点部分，为最优化工艺的判据。即：在烧结温度为1410℃、湿磨时间为48h左右的工艺路线为最优化工艺路线。对于硬质合金再生料来说在这个工艺下生产的产品性能指标为：HRA为89.7，抗弯强度为215 kg／mm²，耐磨性为3.42×10^-2，矫顽磁力为12.5kA／m。4、切削实验表明，再生料与原生料切削性能没有太大的差别；冲击实验表明，再生料冲击韧性比原生料还稍微好一点；但在拉丝实验中再生料性能要差一些，但总体差距不是很大。5、在利用再生料生产不同用途的硬质合金制品时，可以通过适当调节生产工艺来达到原生料制品同等的性能。更多还原

【Abstract】 There are many methods to reclaim waste and old cemented carbide, and the properties of the products prepared by different techniques differ from each other. It is very important to do research on the reclaimed materials and make use of the tungsten resource to the maximum extent. In the present study, Zinc-reclaiming technique was used to reclaim waste and old hard alloy that was supposed to be used in the industrial production. And a abecedarian discussion on how to improve the use-value of the products was made.A research of the influence of the Zinc-reclaiming technique on the quality of the reprocessing mixture was made. The discharge rate of the mixture, the residual quantity of Zn and some other factors which influence the qualities of the material differ with different processing parameters such as the quantity of Zn and so on. Chemical analysis, optical spectrum analysis and otherwise were used to investigate the content of impurities. The particle size average and the distribution of size were tested by many methods. XDR was used to analyse the integrity of the subgrains in the reprocessing WC. And in order to find out the best processing parameters, the changing rules of the hardness, strength and wear-resisting property of the reprocessing material under different wet grinding time and different sinter temperature were studied. And the properties of the wire-drawing dies, the aiguilles and bits made by optimal reprocessing material were compared with those made by virgin material.Adopting appropriate technique parameters and using new furnace can achieve the reduction of the residual quantity of Zn and the improvement in the production efficiency. The content of Zn in the reprocessing material reclaimed by Zinc-reclaiming technique is higher than in the virgin material. However the crystal forms of the reprocessing material is more integrated and its distribution of size is narrower. And these characteristics were helpful to improve the properties of the final products. Because the particle size average, distribution of size and the crystal form of the reprocessing ones were different from the original ones, the processing parameters differ to produce the hard alloy. However the products of reprocessing material produced by optimal processing parameters do not show large drop in the properties than the ones produced by the virgin material. There is little difference between the wire-drawing dies, the aiguilles and bits made by reprocessing material and original material. Therefore the hard alloy made by reprocessing material reclaimed by optimal processing parameters can replace the hard alloy made by virgin material.The major results can be summarized as follows:1. The reduction of the losing of carbide can be achieved by reduce the size of the blocks and using new furnace to improve the efficiency of melting. And appropriate amount of C can be added to reduce the content of oxygen. And the reduction of the Zn residual quantity can be achieved by guarantee the time of melting and the content of Zn.2. The amounts of Si, Mg, Fe, Ca, Ni and so on are higher in the reclaimed material than in the virgin material. There is little difference between the particle size of the reclaimed WC and the grain size of the waste, material. The relationship between the gain size of the alloy and the wet-grinding time is almost linear in a region.3. The strength is higher as the melting temperature increases from 1370℃to 1450℃after wet-grinding. The strength decreases and the hardness increases as the wet-grinding continues from 24h to 72h. The wear-resisting property increases with the increase of the wet-grinding time. And it reaches its maximum at 1390-1430℃. The optimal processing parameter is to melt at 1410℃after wet-grinded for 48h. And the properties of the reclaimed material are as follows: HRA: 89.7, wear-resistance: 3.42×10^-2 , strength: 215 kg/mm²4. There is little difference between the reclaimed material and virgin material in the cutting experiment. And the reclaimed material acts better in the impact experiment but worse in the wire-drawing experiment. Butthe differences are not big.5. The cemented carbide goods produced by reclaimed material can achievealmost the same properties of the goods produced by virgin material though adopting appropriate processing parameters.更多还原