Novel Processing of WC/Co Hardmetals with Simultaneous Improvements in Hardness and Toughness Derived From Nanocrystalline Powder

WC/Co 硬质合金的新颖加工，同时提高纳米晶粉末的硬度和韧性

• 批准号: 0856122
• 负责人: Leon Shaw
• 金额: $ 30万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0856122&HistoricalAwards=false
• 关键词: Novel; Processing; WC; Co; Hardmetals

The research objective of this award is to develop innovative manufacturing methods that can produce novel materials derived from nanocrystalline powder with low costs and superior mechanical properties simultaneously. Specifically, a novel manufacturing process, termed as the Integrated Mechanical and Thermal Activation (IMTA) process, will be utilized to make low cost nanostructured WC/Co powder which will subsequently be densified using the innovative sintering strategy to allow the conversion of nano-WC particles to submicrometer-sized WC platelets. The dense WC/Co cermets with submicrometer-sized WC platelets are expected to offer unprecedented simultaneous improvements in hardness and toughness. To achieve the best improvements, WC platelets will be fabricated to have both high aspect ratio and thin thickness. The thin thickness will limit the slip distance of dislocations and thus provide high hardness, while the high aspect ratio of platelets will offer effective crack deflection and thus result in high toughness. Thin and high aspect ratio WC platelets will be produced via detailed and comprehensive studies of the effects of sintering conditions, the size of the starting WC particles, the Co concentration, the free carbon concentration, and addition of a small amount of dopants. The microstructure of WC/Co with and without doping sintered under various conditions will be characterized in detail to elucidate the formation mechanism of WC platelets and the effect of various dopants and processing conditions. Deliverables include mechanistic understanding of the effects of sintering conditions, the size of the starting WC particles, the Co concentration, the free carbon concentration, and a small amount of dopants on the formation of WC platelets, dense WC/Co cermets with simultaneous improvements in hardness and toughness, engineering students education, and research experience for middle/high school underrepresented minority students.If successful, the results of this research will produce a new generation of low cost and high performance WC/Co cermets with superior hardness and toughness for advanced structural applications by many industries. These novel WC/Co cermets could also open up new opportunities in areas outside their current application windows. The understanding developed from this research will lay a scientific foundation for enhancing anisotropic growth of crystals and can be applied directly to other hardmetals such as WC-Ni, WC-NiCo, and WC-CoCr. The scientific principles discovered can also shed light on the processing and microstructure design of advanced ceramics with the anisotropic grain growth property (e.g., Ti3SiC2, Ti3AlC2, and liquid-phase-sintered Si3N4, SiC and Al2O3). Graduate and undergraduate engineering students will benefit from this project through classroom instruction and involvement in the research. Through specially designed summer programs, middle/high school underrepresented minority students will participate in the research. These summer programs will nurture underrepresented minorities towards positive thinking, increase their interest in science and technology, and motivate them to pursue higher education and become future leaders of the society.

该奖项的研究目标是开发创新的制造方法，这些方法可以生产出源自纳米晶粉的新型材料，同时具有低成本和出色的机械性能。具体而言，一种新型的制造工艺被称为集成的机械和热激活（IMTA）工艺，它将用于制造低成本的纳米结构的WC/CO粉末，随后将使用创新的烧结策略来致密，以允许将纳米WC颗粒转换为亚尺寸尺寸的WC降压液。预计具有亚微米大小的WC血小板的密集的WC/CO Cermets有望在硬度和韧性方面提供前所未有的同时改善。为了获得最佳的改进，WC血小板将被制造成高纵横比和较薄的厚度。较薄的厚度将限制位错的滑动距离，从而提供高硬度，而高血小板的高纵横比将提供有效的裂纹挠度，从而导致高韧性。 WC血小板将通过对烧结条件的影响，起始WC颗粒的大小，CO浓度，游离碳浓度以及添加少量的掺杂剂的效果来生产较薄和高的长宽比WC血小板。 WC/CO的微观结构将在各种条件下进行和不掺杂的掺杂烧结，以详细描述，以阐明WC血小板的形成机理以及各种掺杂剂和加工条件的效果。可交付成果包括对烧结条件的影响，起始WC颗粒的大小，CO浓度，游离碳浓度的大小，少量的掺杂剂对WC血小板形成的少量，WC/CO的少量，同时改善硬度和韧性的学生，以及一位较小的学生的研究经验，这是一位培养的学生，这是一位培养的学生，这是一位成功的学生。以及高性能的WC/CO Cermets具有出色的硬度和韧性，用于许多行业的先进结构应用。这些新颖的WC/CO Cermets还可以在其当前应用程序窗口以外的地区开辟新的机会。这项研究得出的理解将为增强晶体各向异性生长的科学基础，并可以直接应用于其他硬质量，例如WC-NI，WC-NICO和WC-CORC。发现的科学原理还可以阐明具有各向异性谷物生长特性（例如Ti3SIC2，Ti3Alc2和液相插入的SI3N4，SIC和AL2O3）的高级陶瓷的加工和微观结构设计。研究生和本科工程专业的学生将通过课堂教学和参与研究中受益。通过专门设计的夏季计划，中/高中代表性不足的少数民族学生将参加这项研究。这些夏季计划将培养代表性不足的少数民族，以积极思考，增加对科学和技术的兴趣，并激励他们从事高等教育并成为社会的未来领导者。