热等静压对铸件致密化及组织演变机理的影响研究

研究了铸件制品的热等静压致密化机理,分析了铸件制品热等静压的致密化模型,综合应用合金的蠕变理论和粉末冶金的烧结理论,利用现有的物理和数学模型对铸件在热等静压过程中的内部孔洞类缺陷闭合过程机理进行了阐述。确认了热等静压过程中起主要致密化作用的孔洞形变机制,为选择制定合适的热等静压工艺参数提供了理论参考。     

热等静压(HIP)技术和设备的发展及应用

从热等静压设备的组成部分及安全保护设计方面简要介绍国外该设备的发展,并介绍国外热等静压设备的特点。在国内热等静压设备的发展方面,简要介绍研发和为国内外用户制造热等静压设备并成功投入使用的情况。在热等静压技术应用方面,主要介绍该技术在铸件致密化处理、粉末冶金、热等静压连接和复合以及在重要工程项目中的实际应用。     

近年来热等静压(HIP)处理与应用发展趋势

自1970年以来,高温合金、不锈钢及钛等主要的大型粉末冶金(PM)近终形零件,已广泛采用热等静压(HIP)处理,从1970年以来,已安装的约有1 000台热等静压装置(这些HIP装置约50%是用于研究与开发的)。HIP装置也用于使铸件致密化处理、扩散粘结与包层及使硬质合金致密化。这篇述评主要着眼于HIP技术和粉末材料应用的发展趋势。     

生产成本低的粉末冶金法

美国缅因州Gorham国际公司已就一项称之为“压力辅助烧结”(PAS)的粉末金属加工新工艺获得美国专利(专利号4,591,482)。据称,该工艺可以低于烧结或烧结+热等静压工艺的成本生产出完全致密的粉冶件。采用远比热等静压工艺所要求的压力低得多的等静压可使许多合金完全致密化,其机械性能优于锻件、铸件和机加工件。 PAS工艺不仅仅是简单的低压热等静压(HIP)工艺。它是在PALS工艺过程中的正确时间和温度下施加适当的压力进行烧结,从而生产完全致密的粉冶件。相比之下,热等静压工艺采用很高的压力来克服材料的屈服强     

铸造高温合金的热等静压致密化机理

本文研究了铸造高温合金的热等静压致密化机理,综合应用高温合金的蠕变理论和粉末冶金的烧结理论,导出了以γ′沉淀相强化的铸造高温合金的热等静压致密化速率与热等静压工艺参数的解析表达式。在K18铸造高温合金上进行的不同温度、压力和时间的热等静压实验表明,实验值与理论值符合良好。     

Ti-5Al-2.5Sn合金粉末热等静压压坯的致密化行为及性能

粉末冶金近净成形工艺能够制备性能要求高、结构复杂的钛合金构件.将洁净Ti -5Al -2.5Sn预合金粉末封装在低碳钢材料制造的包套中,采用热等静压进行了粉体的致密化,研究了粉末在热等静压过程中的致密化行为.由于包套对热等静压压力的屏蔽效应,致密化过程后观察到了粉末/包套体的不均匀变形;通过有限元仿真也预测到包套对包套...     

热等静压铁钴镍基高温合金的显微组织和力学性能

以气雾化（gas atomization,GA）粉末为原料,采用热等静压（hot isostatic pressing,HIP）致密化烧结工艺制备Fe18Ni23Co25Cr21Mo8WNbC2铁钴镍基高温合金,研究热等静压温度对致密化Fe18Ni23Co25Cr21Mo8WNbC2粉末高温合金金相组织、力学性能和断口形貌的影响。结果表明:热等静压技术制备的高温合金致密化程度很高,烧结体由（Fe,Ni）固溶体相和弥散分布的M6C碳化物强化相组成;热等静压温度为950~1050 ℃时,烧结体的密度、力学性能随着热等静压烧结温度的提高而提高;当热等静压温度达到1100 ℃时,致密化烧结体晶粒组织明显长大,其力学拉伸性能降低;致密化烧结体的室温拉伸断口以穿晶断裂为主,局部区域晶粒被拉伸开裂,650 ℃高温断口为穿晶断裂和沿晶断裂的混合形貌,基体相存在沿应力方向被拉长的韧窝。     

热等静压烧结温度对Mo–Na合金性能影响

采用热等静压烧结法制备Mo–Na合金，研究了热等静压烧结温度对Mo–Na合金显微组织、硬度、密度及Na质量分数的影响，分析了Mo–Na合金热等静压烧结的致密化过程。结果表明:采用热等静压烧结法制备的Mo–Na合金显微组织细小均匀，平均晶粒尺寸在10 μm以下。随着热等静压烧结温度的升高，相对密度及硬度随之升高，在1100 ℃时达到最大，分别为99.58%和HRA 54.50，热等静压过程中液相的形成对Mo–Na合金的致密化起到了重要作用。热等静压过程很好地避免了低熔点Na金属高温烧结过程中的挥发，在1100 ℃烧结后Na质量分数基本无变化。     

热等静压技术在金属材料加工领域的应用及发展趋势北大核心

材料是科技发展的基石,金属在材料领域占有重要的地位,而高端金属材料的制备离不开一项专有技术——热等静压。热等静压过程一般没有液相出现,在固态下实现原子间的扩散,进而实现冶金结合。热等静压按照加工原理分为致密化处理、扩散连接和粉末冶金三类应用,其中近终成形是粉末冶金应用的高端形式。归纳总结了热等静压技术的研究进展,分别对致密化处理应用领域、扩散连接应用现状、粉末冶金制品的应用趋势进行了阐述,为寻求高端金属材料制备手段的工程技术人员提供参考。     

ITO靶材热等静压致密化工艺研究

用化学共沉淀法制备的ITO复合粉末经冷等静压成形后进行热等静压致密化,热等静压时采用碳钢作包套,采用铜箔作隔层,实验研究了热等静压主要工艺参数对ITO陶瓷靶材致密化的影响,实验结果表明:靶材的相对密度在大约1000℃处有一峰值;相对密度随压力增加而增加;当保温温度较低时,适当延长保温时间有利于提高密度;当保温温度较高时,延长保温时间反而使密度降低,分析了ITO在高温下的分解行为以及这种行为对致密化的作用,还解释了ITO复合粉末部分脱氧使ITO陶瓷半导化的机理。     

熔炼次数对M17返回料合金成分、组织和性能的影响

实验结果表明,M17铸造高温合金(%:0.16C、8.79Cr、5.79A1、4.93Ti、3.29Mo、15.20Co、0.78V、0.015B、0.073Zr、0.002S、0.001P、0.001 1O、0.001 0N)经25 kg真空感应炉返回重熔后,Si含量随重熔次数的增加而略有增加,合金中主要元素和其它杂质元素S、P、H的含量变化不大,而氧、氮略有增加;合金中初生碳化物由新合金中的草书体逐渐向返回合金块状转变,初生碳化物的遗传性堵塞合金凝固时的补缩通道,使返回料合金的疏松倾向增大,高温塑性下降较大。     

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.