I-Corps: Commercialization of a Decontamination Process for Powders for Transparent Ceramics

开发了一种新的净化工艺，并获得了专利，以减少陶瓷粉末中不需要的杂质含量。这一过程去除了硫和氯等杂质，这些杂质在很大程度上被忽略了，无法用商业上使用的传统净化工艺来去除。因此，即使是市面上可以买到的“超高纯度”粉末，也常常含有相当数量的此类杂质。所提出的提纯工艺已成功地应用于镁铝尖晶石(镁铝尖晶石)，这是NASA和国防部的首选材料，用于各种需要高透明和高强度材料的国防和航空航天应用。与目前用于此类应用的防弹玻璃相比，使用尖晶石可能会在重量和厚度减半的情况下实现更好的防弹性能。这将在各种方面产生显著的有利影响，如降低维护成本和延长部件的寿命、节省能源/燃料以及提高可利用尖晶石部件的车辆/航天器的有效载荷能力。建议的专利工艺已成功地在实验室中使用，以一致地生产杂质含量足够低的粉末，以便进一步加工，而无论起始粉末中的杂质含量如何。人们相信，这一专利工艺将为大规模生产尖晶石和其他陶瓷的大型整体式本体提供一种经济高效、可扩展的解决方案，从而促进尖晶石的商业化。这将使大量服务于这一市场的工业制造商受益。新的提纯工艺包括在超高真空中处理收到的粉末，并同时加热或不同时加热较长时间。该工艺不会改变已经针对特定应用进行优化的粉末的物理特性，如振实密度或粒度分布。利用处理后的粉末，仅通过热压就可以获得接近理论密度和透明度的尖晶石样品，而不需要添加任何烧结助剂。目前的加工策略包括使用烧结助剂来获得理论密度和透明度，这总是会因为异常的颗粒生长而导致机械性能的下降。当前处理策略中的另一个处理步骤涉及在高温下的后热压热等静压步骤，以去除残余气孔率。尽管这一步骤在零件中产生了接近理论上的透明度，但它导致了加工温度下的异常晶粒生长，并显著增加了尖晶石零件的生产成本。专利方法可能会避免这种复杂的因素，但需要进一步评估才能在商业规模上有效和可行。

A novel purification process has been developed and patented to reduce unwanted impurity content in ceramic powders. This process removes impurities such as sulfur and chlorine which have largely been neglected and cannot be removed by traditional purification processes utilized commercially. As a result, even the 'ultra-high purity' powders that are commercially available often contain significant amount of such impurities. The proposed purification process has been successfully applied to magnesium aluminate spinel (MgAl2O4), a material of choice for NASA and DOD for various defense and aerospace applications for which highly transparent and high strength materials are required. In comparison to the ballistic glasses, which are currently utilized for such applications, an improved ballistic performance at half the weight and thickness can be potentially achieved utilizing spinel. This will have a significant beneficial effect in various ways such as reducing the cost of maintenance and increasing the life-time of the components, energy/fuel savings and increase payload capacity of vehicles/spacecraft where spinel parts can be utilized. The proposed patented process has been successfully utilized in laboratories to consistently produce powders with impurity content that is sufficiently low for further processing, irrespective of impurity content in the starting powder. It is believed that the patented process will invigorate the commercialization of spinel by providing a cost-effective, scalable solution for the mass production of large monolithic bodies of spinel and other ceramics. This would benefit a large number of industrial manufacturers serving this market.The novel purification process involves treating as received powders in ultra-high vacuum with or without concurrent heating for extended periods of time. The process does not modify the physical characteristics of the powders such as tap density or particle size distribution that are already optimized for specific applications. Utilizing the processed powders, it is possible to achieve near theoretical density and transparency in the spinel samples by hot-pressing only without the addition of any sintering aids. Current processing strategies involve use of sintering aids to achieve theoretical density and transparency that invariably lead to degradation of mechanical properties because of abnormal grain growth. Another processing step in the current processing strategies involves a post hot-pressing hot-isostatic pressing step at high temperatures to remove residual porosity. Although this step produces near theoretical transparency in the parts, it results in abnormal grain growth at the processing temperatures and significantly increases the production cost of the spinel parts significantly. The patented process can potentially avoid such complicating factors, but needs further evaluation to be efficient and viable at a commercial scale.