SHS陶瓷内衬复合钢管工艺研究进展

概述了离心、重力分离自蔓延高温合成技术(SHS)的基本原理,总结了SHS技术制备陶瓷内衬复合钢管的优点,从预热与烘干、设备、电磁场及添加剂四个方面综述了复合钢管的研究现状,并对其发展前景进行了展望。     

CrO3、CuO对SHS陶瓷衬层复合钢管组织和性能的影响

采用SHS铝热-重力分离法制备了陶瓷衬层复合钢管。在SiO2、NaF质量分数均为4％的条件下，研究了CuO、CrO3等添加剂对陶瓷内衬致密度、组织和性能的影响，并对二者的影响进行了比较。结果表明，在铝热剂为Al-Fe2O3 4％SiO2 4％NaF 4％CrO3的条件下，陶瓷衬层复合钢管具有较好的结合强度和耐腐蚀性能。     

SHS法陶瓷衬里复合钢管的研究

介绍了国内外 SHS 法陶瓷衬里复合钢管的研究现状,分析了存在的问题,指出了今后的研究方向。     

SHS反应熔粘法制备金属基陶瓷涂层管

用自蔓延高温合成(SHS)在钢管内壁生成Al_2O_3陶瓷涂层,制备了金属/陶瓷复合管。选择合适的添加剂及添加量,可以显著改善陶瓷层的涂覆质量。测试了复合管的抗热冲击性能。     

陶瓷内衬复合管的自蔓延高温合成技术

介绍了自蔓延高温合成(SHS)的离心技术和重力分离技术,着重阐述了陶瓷内衬复合钢管的合成机理。认为陶瓷内衬的自蔓延高温合成过程需要经历铝热燃烧过程、液相分离过程和陶瓷内衬凝固过程,合理地控制这 3个基本过程,就可以极大地改善复合管的组织结构。同时,还对影响合成陶瓷内衬致密化的因素 (预热温度、燃烧合成温度、稀释剂和化学激活剂)进行了分析、探讨。     

SHS法陶瓷内衬复合钢管及其力学性能的研究

采用重力分离-自蔓延高温合成技术,制备了Al2O3-Fe-Cr陶瓷内衬复合钢管,分析了复合钢管的结构及组成,探讨了其对复合钢管耐蚀性和力学性能的影响。结果表明:钢管-过渡层-陶瓷涂层的三层结构可以有效缓解残余应力,提高复合钢管的结合质量;陶瓷涂层的组成分布在一定程度上增强了复合钢管的耐蚀性,并改善了其力学性能。     

防腐、耐磨滚塑复合钢管技术

介绍了滚塑技术、滚塑复合钢管的优点.阐述了交联型聚乙烯滚塑复合钢管、聚苯硫醚滚塑复合钢管、改性超高相对分子质量聚乙烯滚塑复合钢管的性能和特点.     

自蔓延高温合成TiC/Fe金属陶瓷结构复合材料的研究

以C、Ti、Fe粉末为原料,采用自蔓延高温合成技术制备TiC/Fe金属陶瓷结构复合材料。笔者研究了稀土的加入及加入量对SHS反应组织形态影响的因素,预制块的压实度对SHS反应强烈程度的影响。实验结果表明:在SHS反应铸造方法合成的TiC/Fe复合材料表面的TiC颗粒呈理想孤立球状分布,Al_2O_3呈光亮的不规则形状。TiC/Fe表面复合材料结合紧密,从基体到复合层逐渐呈梯度过渡。稀土的加入使高温自蔓延反应组织晶粒得到细化,加入量过高,会抑制自蔓延反应的反应强度和剧烈程度,使表面复合层与基体结合疏松,结合厚度减小。TiC/Fe表面复合材料硬度远远高于基体,且从基体到复合层也呈现梯度分布。     

SiO2/CrO3对SHS陶瓷复合钢管力学性能的影响

采用重力分离自蔓延高温合成技术,制备了陶瓷内衬复合钢管,研究了添加CrO3和SiO2对陶瓷复合钢管的压溃强度、压剪强度、陶瓷层相对密度、显微硬度的影响。结果表明：添加SiO2可以通过增加低熔点相来提高复合钢管的力学性能,以CrO3部分取代Fe2O3可以通过升高反应温度来提高复合钢管的力学性能。同时加入4％SiO2(质量分数,下同）和8％CrO3,可以获得性能优良的陶瓷内衬复合钢管。     

SHS技术发展的概况

本文概括介绍了SHS技术原理、工艺特点及研究现状,并提出了SHS工艺存在的问题及今后研究的重点。     

SHS in the Al-SiO<Subscript>2</Subscript>-C system: The effect of additives

Explored was the effect of various additives on SHS reactions in the Al-SiO₂-C system. Dilution of basic green mixtures with alumina-containing additives (bentonite, kaolin, and industrial aluminum oxide) was found to decelerate SHS reactions and affect the composition/properties of combustion products. It has been shown that SHS reactions in the system under study can be activated upon addition of heat-generating additives such as carbonates, oxides, and boron- or fluorine-containing compounds. The best results were obtained for fluorine-containing additives. Discussed was also the effect of additives on phase compositions of synthesized materials.     

Nitride formation during combustion of Ti-TiO2 and Ti-Al powder mixtures in air under SHS conditions

Nitride formation during SHS combustion of a micron-size titanium powder and its mixtures with additives in air was studied. It was shown that the yield of TiN Ti powder was higher for SHS combustion in air than for SHS combustion of powders of the same degree of dispersion in nitrogen. The mechanism of formation of TiN is probably determined by the reaction of the intermediate product TiO with atmospheric nitrogen. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 5, pp. 131–135, September–October, 2008.     

法治环境下塑料技术的创新与发展

通过解析国内外各项针对塑料制品的规章制度,全面分析了塑料制品中存在的单体及助剂对环境及人类健康的危害,提出了塑料行业从业人员应熟知法规内容、掌握标准方法、建立溯源管理体系、大力发展去重金属化、高相对分子质量化的助剂产品,提升助剂的协效作用等建议,以促使塑料行业在法治环境中健康发展。     

Fine TiAl and NiAl powders by SHS with a reduction stage

Fine TiAl and NiAl powders have been synthesized by SHS with a reduction stage. Explored was the effect of green composition, stoichiometric ratio, and additives on the particle size, morphology, and phase composition of resultant powders. Addition of NaCl and excessive Mg was found to suppress crystallization. In the presence of heat-generating additives, such as Mg(ClO₄)₂ and CaO₂, the synthesized powders had a particle size of below 3 μm. The morphology and phase composition of synthesized NiAl powders were investigated upon variation in the Al content of green mixture.      

Influence of CaO<Subscript>2</Subscript> additives on the properties of Fe–WB-based composite lining deposited by centrifugal SHS on the inner surface of steel pipe

Influence of calcium peroxide (CaO₂) additives on the characteristics and properties of composite coatings deposited by centrifugal SHS was investigated. Microstructure and composition of deposited coatings were characterized by SEM, EDX, XRD, and mechanical testing. The additives of CaO₂ and Al were found to markedly improve the properties of deposited composite coatings. Under optimized conditions, the deposited coatings exhibited rather smooth surface, good adhesive strength, and reasonable micro-hardness.     

Effect of additives on the properties of silicon carbide-based refractories obtained by self-propagating high-temperature synthesis (SHS)

The effect of refractory additives (alumina, alumosilicate mortar, and zircon concentrate) on the properties of SHS refractories based on silicon carbide is studied. It is shown that introduction of the additives favors enhancement of the compressive strength of the material. The enhancement is especially efficient in the case of an admixture of zircon concentrate. The resistance of the silicon carbide material to corrosion in slags of titanium production and iron foundry production is improved when the content of the additives is increased from 5 to 30%. The addition of zircon concentrate allows the slag-resistance of the silicon carbide material to be increased by a factor of 6, while the effect of alumina and alumosilicate mortar is less pronounced. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 1, pp. 17–18, January, 1997.     

Time-resolved X-ray diffraction study of SHS-produced NiAl and NiAl-ZrO<Subscript>2</Subscript> composites

NiAl and NiAl-ZrO₂ intermetallic composites were prepared from pressed elemental powders by SHS in a dynamic vacuum. The effect of diluent properties (such as conductivity and grain size) on the parameters of the SHS reaction has been investigated by time-resolved X-ray diffraction (TRXRD). By decreasing the reactivity of the green mixture, these nonreactive additives not only slow down the velocity of combustion front propagation but can also give rise to local melting of the product. Synchrotron radiation was also used to elucidate the reaction mechanism. It has been found that the combustion synthesis of NiAl is triggered by aluminum melting and proceeds via the formation of two transient intermetallic phases, NiAl₃ and Ni₂Al₃. In the final product, only the NiAl phase has been detected.      

自蔓延高温合成的发展前景

介绍了自蔓延高温合成的现状和发展方向,分别从理论和合成技术上对自蔓延高温合成前景进行分析和概述,燃烧过程的动力学研究将成为今后理论研究的热点,在生产技术上电场、磁场、重力对SHS工艺及制品的性能会产生影响。     

磷-氮型极压抗磨添加剂研究进展

总结了磷-氮型极压剂的类型及发展现状,并对国内外磷-氮型添加剂的合成及其在润滑油中的应用进行了文献综述,详细介绍了磷-氮剂的制备方法、应用范围和良好性能,总结了文献中关于磷-氮型添加剂作用机理的报道,并对其发展趋势提出了一些看法。