Xiong Yuandong, Li Ying, Chen Huiting, Qiu Dejin, Wei Shiyu, Saxén Henrik, Yu Yaowei
State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
Process and Systems Engineering Laboratory, Faculty of Science and Engineering, Åbo Akademi University, Henriksgatan 2, 20500 Åbo, Finland.
Materials (Basel). 2022 Aug 10;15(16):5496. doi: 10.3390/ma15165496.
Silicon nitride (SiN) and silicon powder (Si) are two kinds of harmful solid waste in industrial production. As an environmental and low-consumption method, the cold-bonding technique is a novel method to utilize the problem of powder resource cycling. In this experiment, mechanical and high-temperature properties of Si and SiN briquettes were studied after cold bonding. The results are as follows: (1) The compressive strength of the Si and SiN briquettes increased with the improvement of molding pressure. With the same binder (1 wt.%) and water (10 wt.%) addition, the compressive strength of the SiN briquette arrived at 12,023.53 N under 40 Mpa molding pressure, which is much higher than that of the Si briquette (942.40 N). The Si particles are uneven and irregular, which leads to an intense arch bridge effect in the Si briquette and the compressive strength decrease. Compared with Si powder, the particle size and shape of SiN is small, uniform, and regular. The influence of the arch bridge effect is smaller than that in the Si briquette. (2) After being treated at 1473 K for 1 h, the compressive strength of the Si briquette increased to 5049.83 N, and the compressive strength of the SiN briquette had a slight change. The surface of the briquettes was contacted with oxygen and reacted to form an outer shell which mainly contains SiO in the high-temperature treatment. FT-IR results have shown there were no extra impurities in cold-bonded briquettes when using the organic binder. (3) The microstructure of the cross section of the Si and SiN briquettes after high-temperature treatment presented that oxygen entered the briquette through the pores and continued to react with the Si and SiN. The outer shell of the Si briquette grew and thickened continuously with the oxygen spreading in the Si briquette. However, because of the smaller particle size and regular shape, little oxygen diffused in the SiN briquette. The outer shell of the SiN briquette is fairly thin, so the compressive strength did not change too much.
氮化硅（SiN）和硅粉（Si）是工业生产中的两种有害固体废物。作为一种环保且低消耗的方法，冷压成型技术是解决粉末资源循环利用问题的一种新方法。在本实验中，研究了冷压成型后Si和SiN团块的力学性能和高温性能。结果如下：（1）Si和SiN团块的抗压强度随成型压力的提高而增加。在相同的粘结剂（1 wt.%）和水（10 wt.%）添加量下，在40 Mpa成型压力下，SiN团块的抗压强度达到12,023.53 N，远高于Si团块的抗压强度（942.40 N）。Si颗粒不均匀且不规则，导致Si团块中出现强烈的拱桥效应，抗压强度降低。与Si粉相比，SiN的粒径和形状较小、均匀且规则。拱桥效应的影响小于Si团块。（2）在1473 K下处理1 h后，Si团块的抗压强度增加到5049.83 N，SiN团块的抗压强度略有变化。团块表面与氧气接触并发生反应，在高温处理过程中形成了主要含有SiO的外壳。傅里叶变换红外光谱（FT-IR）结果表明，使用有机粘结剂时，冷压成型团块中没有额外的杂质。（3）高温处理后Si和SiN团块横截面的微观结构表明，氧气通过孔隙进入团块，并继续与Si和SiN发生反应。随着氧气在Si团块中的扩散，Si团块的外壳不断生长和增厚。然而，由于粒径较小且形状规则，很少有氧气扩散到SiN团块中。SiN团块的外壳相当薄，因此抗压强度变化不大。
