表层脱立方相梯度硬质合金及其切削应用研究进展

对表层脱立方相梯度硬质合金的研究成果进行了总结。系统地介绍了化学成分、原料粒度、烧结气氛对表层脱立方相梯度硬质合金微观组织、元素分布和性能的影响,概括了表层脱立方相梯度硬质合金作为涂层基体应用及后续涂层梯度硬质合金刀具切削加工应用,并指出研究表层脱立方相梯度硬质合金表面处理技术是挖掘其应用潜力的重要方向。     

梯度硬质合金渗碳前驱体的研究

采用贫碳配料的方法制备了η相均匀弥散分布的梯度硬质合金渗碳前驱基体，通过对渗碳基体显微组织的观察，研究了贫碳量对渗碳基体显微组织的影响。结果表明，对于不同贫碳量的基体，其组织结构都呈均匀分布的WC＋Co＋η的三相组织；η相的含量随贫碳量的增加而增加，η相的形成区域应该为合金中W弥散分布的区域，叩相的形成可看作是在含W的微区内进行原位生成；同时η相的含量及晶粒大小都随烧结温度的升高而增加，WC晶粒也同时随烧结温度的升高而出现长大。     

梯度结构硬质合金的疲劳断裂

采用三点抗弯的方法研究WC-6Co梯度结构硬质合金和均质WC-6Co硬质合金的疲劳行为,探讨疲劳断口形貌与破坏机制的关系。结果表明:梯度结构硬质合金的疲劳裂纹在亚表面萌生;梯度结构硬质合金表层Co相发生明显塑性变形,WC相以沿晶断裂为主;中间层Co相变形也很明显,WC相解理断裂增加;内层Co相塑性变形很少,WC、η相以解理断裂为主;均质硬质合金Co相塑性变形明显,WC以沿晶、解理断裂为主,各部位断口形貌接近;梯度结构硬质合金的疲劳极限比均质硬质合金高约100 MPa;梯度结构硬质合金中疲劳裂纹沿垂直于试样下表面、平行于Co相梯度的方向形核,而均质硬质合金的疲劳裂纹沿平行于试样外表面方向形核。在应力集中效应、循环应力的作用下,Co相的马氏体相变是裂纹在亚表面萌生的主要原因;马氏体相变使Co相成为裂纹形核的快速通道,裂纹沿Co相梯度方向形核。     

超重力对梯度Al-Zn-Mg-Cu合金成分和微观组织的影响

提出了一种制备梯度Al-Zn-Mg-Cu合金的新方法,通过优化实验的工艺参数,在超重力降温离心的条件下结合定向凝固工艺获得具有梯度的成分含量、显微组织及力学性能。基于合金的析出特性,利用超重力技术和温度梯度区间实现冷却凝固过程中α-Al析出相和共晶T相的高效分离,大部分的α-Al析出相集中在试样顶部,而共晶组织主要分布在试样底部。不同密度的析出相在超重力的作用下分布于样品的不同位置,使得增大重力系数和扩大温度梯度有利于获得梯度范围更大的材料。结果表明,在超重力的条件下,降温离心可以在短时间内获得梯度铝合金,从而为梯度铝合金材料的制备提供了新的工艺手段和思路。     

真空渗碳制备双相梯度硬质合金的研究

介绍了采用真空渗碳来制备试样外层为无η相正常组织而芯部为η相、且粘结相钴呈成分梯度分布的双相硬质合金的方法,试验发现,在真空烧结后期引入甲烷与丙酮蒸气的混合气体进行摆式渗碳,是制备该类梯度硬质合金非常有效的方法。     

烧结矿粘结相流动性的研究

以高碱度烧结矿中的铁酸钙粘结相为研究对象，考察了粘结相的流动性和液相生成能力；实验研究了不同nCaO：nFe2O3以及不同氧化镁、二氧化硅和三氧化二铝的铁酸钙粘结相的流动特性和熔化时间。定义粘结相的流动性指数描述铁酸盐粘结相的流动性，用熔化时间来表示粘结相的液相生成能力。结果表明，nCaO：nFe2O3 =1：1时，粘结相的流动性和液相生成能力最好；添加氧化镁使粘结相的流动性和液相生成能力变差；添加适量的二氧化硅或三氧化二铝能改善铁酸盐粘结相的液相生成能力，但二氧化硅和三氧化二铝过多将使粘结相的流动性变差。     

铝电解槽中Marangoni对流研究

Marangoni对流是由界面张力梯度引发的,通常发生在界面张力存在梯度的多相流中.铝电解槽内熔体运动是典型的两相流问题.为此,从工业电解槽中电解质内酸度分析出发,指出该界面上界面张力存在梯度.正是这个梯度引发了铝电解槽中的Marangoni对流.在FLUENT环境下,建立了简单的铝电解槽二维两相流模型对Marangoni对流进行数值模拟.结果表明,电解质/铝液界面张力梯度引发的Marangoni对流对铝电解槽熔体运动和界面变形的影响可以忽略.     

不含氮原料制备脱β层梯度硬质合金的机理研究

采用不含氮原料及微压氮化+真空脱氮烧结工艺制备脱β层梯度硬质合金,并采用扫描电镜及自带能谱仪、电子探针微区分析技术分析不同烧结阶段下硬质合金样品的微观组织结构及成分分布,研究烧结过程中微观组织结构演变规律,总结缺立方相层的形成机制,同时分析富Co层的形成机理。结果表明:在微压氮化阶段,硬质合金中的TiC相被氮化生成了Ti(C,N)相;在之后的脱氮烧结阶段,Ti(C,N)相溶解在液相中,并且发生氮钛的耦合扩散,导致缺立方相层的形成。Co元素的空位扩散及液相迁移机制联合作用形成了富Co层;冷却过程中液相迁移导致了富Co层内部不同区域之间Co含量的差异。     

Ce对热浸镀铝HP40Nb钢氧化行为及组织的影响研究

通过SEM,EDS和XRD研究了Ce对HP40Nb热浸镀铝层组织结构和高温抗氧化性能的影响.结果表明,热浸镀过程中添加质量分数1％Ce促进了镀层外层中Fe2Al5和Fe4Al3Ce相的生成,抑制了内层Fe2Al5相长大;在1 000 ℃/4 h扩散处理过程中,Ce促进了γ向α相的转变以及α相中Ni3Al相的析出,并在渗层内层中生成富Ce相;800C/360 h氧化后,Ce促使渗层外层生成少量Fe2Al5和Cr3Si相,并使渗层外层组织均匀致密;1000℃/360 h氧化后,Ce促使α相长大导致渗层中生成大量的σ相.800℃氧化实验发现1％Ce使渗层组织致密,提高了渗层高温抗氧化性;1 000℃氧化实验发现1％Ce促进了渗层中σ相的生成,阻碍了Al原子的内扩散,保证了氧化过程中渗层表面生成α - Al2O3所需铝含量.     

Sn/Ni液/固扩散偶的界面反应

用Sn／Ni液／固扩散偶研究了Sn液体和Ni基体之间的界面反应和生成相序列。结果表明：Sn／Ni液／固扩散偶在773K退火，其液／固界面上首先生成Ni3Sn4相。而在873K退火15min，首先生成Ni3Sn2-HT（高温）相；再随退火时间延长至60min，在液相和Ni3Sn2-HT的界面上生成Ni3Sn4相；当退火时间再次延长至240min，又在Ni3Sn2—HT相与fee（Ni）的界面上生成Ni3Sn相。采用最大驱动力模型，利用Thermo-Calc软件和已有的Ni-Sn二元数据库对Sn／Ni液／固扩散偶的界面反应过程和生成相序列进行了计算与预测，预测结果和实验结果吻合良好。     

China's Major Non-ferrous Metals Imports & Exports

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Zinc Production by Province in 2014

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80% of Chinese Firms Purchasing Overseas Mines Ended up in the Red

<正>Minmetals Resources acquired the world’s largest copper mine under construction for USD5.85 billion.One after another,listed companies Jien Nickle,China Molybdenum and Chihong Zinc and Germanium raised money to get involved in overseas mining projects…SOEs and private enterprises are engaged in a frenzy of overseas mine purchasing.A reporter with Economic     

Copper Processing Profit Dropped Sharply,Copper Consumption Will Face Impact in the Second Half of the Year

正Judging from China’s copper consumption field,the biggest consumption unit is electric power,which accounts for 47%of total consumption;it is followed by light industry sector,including household electrical appliance,machinery,durable goods and hardware etc,which accounts for 22%of total consumption;followed by transportation field,     

Central Geological Prospecting Fund Newly Added 16.47 Million Tonnes of Bauxite in 2013

正In 2013,the Central Geological Prospecting Fund(CGPF)Project newly discovered 15 ore fields,including 3 large above ore fields,and 5medium sized ore fields.The reporter learned from the recently published"Annual Report of Central Geological Prospecting Fund Project(2013)"that,from 2006 to 2013 the CGPF     

Manufacturers of Copper Tube for Central Air Conditioner Use Face Mounting Pressure in the Final Quarter of the Year

正This year,the investment growth rate of real estate industry continued to slow down,sold area of commercial housing also dropped significantly,which brought huge pressure to the domestic air conditioning manufactures.In the first half of the year,by relying on high growth in national financial expenditure,along with investment in public infrastructure     

Xinjiang Ranks No.1 in Production of Primary Aluminum in China

正Kang Yi,Honorary Chairman of China Nonferrous Metals Industry Association,said recently at the Forum on Development of the Non-ferrous Metals Industry in Central and Western China held in Zhengzhou that,as more and more electrolytic aluminum factories in Xinjiang came into operation,the electrolytic aluminum output of Xinjiang had reached2,275,000 tons in the first 7 months this year,     

Shenhuo Coal Industry and Electricity Power Completed800,000 t/a Aluminum Project in Xinjiang

正"Xinjiang project has been completed according to schedule,but total completion and total start of production are two different concepts,after completion it still needs a gradual process of reaching production target."On the morning of November 3,Shenhuo Coal Industry and Electricity Power told investors the above statement on the investor interaction platform.     

Guangdong Metal Transaction Center has Become the Second Largest Precious Metal Transaction Platform Nationwide

正The reporter learned from Guangdong Province Precious Metal Transaction Center that in 2013the Center maintained healthy development momentum,and had become the second largest precious metal transaction platform in China in terms of market size;currently Guangdong is quickening steps of financial innovation for the Center,aiming to build a transaction center with international core competitiveness.     

Seven Rare Earth Projects Involving Close to 3 Billion Yuan Investment Landed In the HighTech Zone

正On May 22,Baotou Rare Earth Industry Cooperation Consultation MeetingProject Agreement-signing Ceremony was held in Ningbo,nearly 40 enterprises from Ningbo,Guangdong,Hunan,and Shanxi participated in project consultation.After multi-lateral communication,agreements were signed for a total of 7 rare earth projects successfully.