不同粉末粒径粉芯丝材双丝电弧喷涂声发射技术分析

阻碍热喷涂技术广泛应用的最大障碍之一就是在喷涂过程中缺乏在线控制方法。热喷涂涂层的优化方法是通过对喷涂参数和喷涂参数一涂层性能相关性的经验性调整。而对于一些固有参数是无法调整的,如双丝电弧喷涂过程中的焰流波动和雾化喷嘴磨损,尽管这些参数对涂层的质量有巨大影响,但出于简化目的通常系统地忽略不计。本文中采用声发射分析法,基于所获得的声信号对不可调节参数的影响进行分析。将声发射感应器同时安装在基体和喷嘴上,使得对喷涂过程中的声信号变化进行简单测定成为可能。当增加电流时,一个降低的声信号被记录下来,从而可对不可控参数、声信号和涂层质量之间的相关性进行分析研究。这项研究将有助于探索喷涂过程中的在线控制方法。     

电弧喷涂技术的发展及应用

叙述了电弧喷涂技术原理，工艺过程，涂层结构和技术发展现状及应用的概况，在贵金属领域中将有重要的应用前景。     

工艺参数对电弧喷涂NiAl涂层结合强度的影响

以涂层结合强度为判据,采用Ni-Al丝材和PARXAIR-9935电弧喷涂系统制备镍基涂层,通过正交试验对电弧喷涂NiAl合金工艺进行了优化。利用在线检测系统对焰流的强度、粒子的速度和温度进行检测,通过金相显微镜、扫描电镜、能谱仪等手段对涂层和断口形貌进行分析。结果表明,喷涂电流、喷涂电压、雾化空气压力、喷涂距离对NiAl合金涂层结合强度具有不同程度的影响,确定优化后的工艺参数为喷涂电流150A,喷涂电压27V,雾化空气压力0.6MPa,喷涂距离150mm。在优化工艺参数条件下,电弧喷涂NiAl合金涂层组织呈现出典型的层状结构;并且随着涂层厚度的增加,结合强度呈线性下降,其最大结合强度可达39.8MPa。     

锅炉受热面管的复合涂层防护技术

针对燃煤电站锅炉受热面管磨蚀严重，导致泄露、爆管等事故而被迫停炉检修的情况，根据受热面管的形状、工况条件和使用环境状况，对电弧喷涂工艺以及对若干用于锅炉抗高温磨蚀的喷涂丝材所制备涂层的微观组织结构、硬度、涂层结合性能以及耐冲蚀磨损性能和高温腐蚀性能等进行了深入的研究。结果表明，以超音速电弧喷涂NiAl丝材作为结合底层、金属-陶瓷材料或高Cr材料作为功能层、并辅以高温封孔的复合涂层制备技术，可提高锅炉运行的可靠性和经济性。     

粉芯丝材电弧喷涂的不稳定性分析

双丝电弧喷涂时,丝材顶端根据被加热状态可分为三个不同区域。其中,丝材顶端最外层被电弧直接加热（Ⅰ区）,这个区域的丝材完全熔化。由于传热效应使得相邻区域（丝材根部方向）的温度升高,从而产生软化区（Ⅱ区）。而与软化区相邻处（丝材根部方向）,传递的热量又软化了丝材并产生持续的变形区（Ⅲ区）,变形是由雾化气体所施加的动力产生的。采用高速摄像系统观察不同运行条件下丝材熔化、金属破碎并粒子形成的过程：Ⅰ区液态金属直接雾化成为很小的液滴,其尺寸是由熔化金属的特性和所施加的雾化气体压力所决定的,软化区是在阴阳极部位的金属薄片的源头。粉芯丝材的金属薄片要比实心丝材的尺寸小。受挤压作用形成的金属薄片形成二次引弧效应,因此增加了电弧喷涂过程的稳定性。本文分析了喷涂参数的影响、填充粉芯对熔化行为的影响、粒子形成以及喷涂过程的不稳定性,并将粉芯丝材和实心丝材的喷涂进行了对比。研究结果有利于提高双丝电弧喷涂模型的精度,并且可以通过优化喷管几何形状来增强金属液滴的雾化效果。     

新型Cu基丝材涂层组织性能的研究

利用电弧喷涂工艺制备了一种新型的Cu基涂层,利用OM、SEM、XRD、DSC、HRC、热震等手段研究了该丝材、涂层的形貌组织、相组成、熔点、力学性能等。     

Ni-20Al 丝材制备及涂层微结构特征研究

开发了三种不同结构的 Ni-20Al 丝材, 对其火焰喷涂工艺性和涂层微结构特征等进行分析, 并与商用 Metco 405NS 丝材及所制备的涂层进行了对比。 结果表明, 丝材结构影响了火焰加热时热量由丝材表面向芯部的 传导, 导致丝材熔化状态产生显著差异, 进而决定了喷涂焰流的稳定性以及相关涂层组织的均匀性。 其中, 采用 轧制拉拔包丝技术制备的 Ni-20Al 丝材, 呈现出优异的喷涂工艺稳定性, 所制备的涂层组织均匀, 平均显微硬度 和结合强度分别可达 348.3 HV0.05、 62 MPa, 与 405NS 丝材制备涂层性能基本一致, 具备了较好的应用潜力。     

电弧喷涂工艺的试验研究

研究了电弧喷涂电压、电流对涂层的成分、组织、性能的影响以及表面预处理、预热、后热处理对涂层结合强度的影响。结果表明：Nig5A15涂层由大量镍铝固溶体、少量含Ni3Al、NiAl的金属间化合物或氧化物等组成。3Crl3涂层由马氏体基体、铬铁氧化物等组成；电弧喷涂Ф2mm3Crl3丝材的适宜电压、电流为28～35V、170～180A；提高预处理毛化质量、喷涂打底层、严格控制基体的热量输入有利于提高涂层结合强度。     

水冷壁管喷涂铝涂层的应用研究

介绍了电弧喷涂在水冷壁管制备铝涂层的工艺，分析了水冷管的腐蚀状况及铝涂层的防腐性能，探讨了电弧喷铝的特点及相关工艺的选择。     

电弧超音速喷涂技术在锅炉水冷壁防护上的应用

电弧超音速喷涂是以电弧为热源,将金属丝熔化并用气流雾化,使熔融颗粒高速喷射到工件表面形成涂层的一种工艺,采用该工艺在锅炉水冷壁喷涂涂层,用于高温防腐,该涂层具有优异的高温耐蚀性能和良好的耐磨性能。     

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.