Basic understanding of materials synthesis by thermal plasmas

热喷涂在北美是一项价值数十亿美元的活动。热喷涂的大多数问题是为现有材料提供更高的硬度，优越的耐热性，耐腐蚀性，磨损或滑动性能方面的局部优势。随着热喷涂研究和开发的不断进步，其应用从航空航天工业发展到采矿、纸浆和造纸、化学工业和其他工业，以及不太明显的骨科和牙科应用。所有的涂层都必须设计成能够在非常恶劣的环境中生存，并且需要不断改进以减轻重量，降低成本并降低维护成本。随着航空航天和汽车工业的研究投入，基材质量不断提高，涂层也在进一步发展。因此，工业需要新的组合物和新的微观结构或纳米结构，特别是在考虑技术陶瓷材料时，通常组合物最多包括2到3个元素，因为这些材料很难用传统的加工方法加工。最近，美国国家航空航天局开发了一种新型热障涂层，它的导热性只有目前最先进材料的一半。这一发展是通过使用与纳米结构相关的专利四元素陶瓷成分来实现的，它可以简单地取代今天的材料，几乎是材料成本的一半，重量和应用时间的一半。本课题通过开发应用于热喷涂的组合无机化学工艺，解决了新涂层材料（特别是陶瓷基）的合成和发现问题。有必要进行这项研究，因为它将能够在未来帮助我们的行业获得创新的涂层材料，这将使我们的产品在国际市场上更具竞争力。

Thermal spraying is a multi billion dollars activity in North-America.  Most of the issues with thermal spraying are to provide to existing materials a localized benefit in terms of higher hardness, superior heat, corrosion resistance, wear or sliding performance.  As thermal spraying research and development is progressing, then the applications evolved historically from the aerospace industry to the mining, pulp and paper, chemical industries and others and also to less visible orthopaedic and dental applications.           All the coatings have to be engineered to survive to a very hostile environment and need always to be improved to save weight, costs and to decrease the maintenance costs.  As the substrate materials quality are progressing with the research invested by the aerospace and automotive industry, so must also the coating being further developed.   New compositions and new microstuctures or nanostructures are thus needed by the industry and especially when considering technical ceramic materials, usually compositions include 2 to 3 elements at the maximum, because those materials are difficult to process by traditional processing methods.  Recently NASA developed a new class of thermal barrier coatings which exhibit half the thermal conductivity of the state of the art materials.  This development was possible through the use of a patented four elements ceramic composition associated to a nanostructure which can simply replace the todays materials with almost half of the materials cost and half of the weight and the application time.         The proposed research addresses the problematic of new coating materials synthesis and discovery (especially ceramic based) by developing the process of combinatorial inorganic chemistry applied to thermal spraying.  There is the need for this research as it will be able, in the future, to help our industry to have access to innovative coating materials which will make our products more competitive on the international market.