Effect of HEA/Al composite interlayer on microstructure and mechanical property of Ti/Mg bimetal composite by solid-liquid compound casting

In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer.The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis.Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg,which is conducive to the formation of solid solution,especially when the thickness of HEA is 800 nm.With the increase of casting temperature from 720 ℃ to 730 ℃,740℃,and 750 ℃,α-Al(Mg),α-Al(Mg)+Al3Mg2,Al3Mg2+Al12Mg17,and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal,respectively.When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 ℃,the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.

Study on liquid-liquid bimetal composite casting hammers

Crusher hammers for the mineral processing industry must meet the demands of both high wear resistance at the hammer head and high impact toughness at the hammer handle. The crusher hammers made of Hadfield steel have typically low service life of less than 40 hours. To solve the problem, a kind of bimetal crusher hammers made of high chromium cast iron(HCCI) and low alloy steel(LAS) has been successfully developed by using liquid-liquid composite casting. The microstructure and composite interface bonding was analyzed using optical microscope, SEM, EDX and XRD. Micrographs indicate that the composite interface is metallurgically bonded with a zigzag shape across the boundary and without unbound region or void. After heat treatment, the composite hammers have shown excellent properties. The hardness of HCCI is at least 63 HRC and its αk is greater than 3.5 J·cm-2; the hardness of LAS is greater than 35 HRC and its αk is no less than 80 J·cm-2. Diffusion of elements takes place at the interface and forms a transition region. The micro hardness increases from LAS to the interface and then to HCCI. Wear comparison was made separately between the bimetal composite hammer and a Hadfield steel hammer in two quarries of Jilin province and Liaoning province. The results showed that the liquid-liquid bimetal composite hammers did not have the falling off of hammer head or impact fracture phenomenon, and their service life was 3.75 times as long as that of the Hadfield steel hammers.

High Cr white cast iron/carbon steel bimetal liner by lost foam casting with liquid-liquid composite process

Liners in wet ball mill for mineral processing industry must bear abrasive wear and corrosive wear, and consequently,the service life of the liner made from traditional materials,such as Hadfield steel and alloyed steels,is typically less than ten months.Bimetal liner,made from high Cr white cast iron and carbon steel,has been successfully developed by using liquid-liquid composite lost foam casting process.The microstructure and interface of the composite were analyzed using optical microscope,SEM,EDX and XRD.Micrographs indicate that the boundary of bimetal combination regions is staggered like dogtooth,two liquid metals are not mixed,and the interface presents excellent metallurgical bonding state.After heat treatment,the composite liner specimens have shown excellent properties,including hardness>61 HRC,fracture toughnessα k >16.5 J·cm-2 and bending strength >1,600 MPa.Wear comparison was made between the bimetal composite liner and alloyed steel liner in an industrial hematite ball mill of WISCO,and the results of eight-month test in wet grinding environment have proved that the service life of the bimetal composite liner is three times as long as that of the alloyed steel liner.

Formation mechanism of bimetal composite layer between LCS and HCCI

A low carbon steel(LCS)/high chromium white cast iron(HCCI) bimetal wear plate about 20 mm in thickness was prepared by liquid-liquid bimetal composite casting technology to substitute for the welding wear plate. A clear and distinguishable composite layer between the LCS and the HCCI was detected with SEM, and the composition and phase were analyzed through EDS and XRD. The composite layer was composed of three sublayers from the LCS to the HCCI: pearlite transition layer, composite layer, and HCCI transition layer. The Vickers hardness from the pearlite transition layer to the HCCI transition layer was 360 HV to 855 HV. The austenite grows as dendrites between the composite layer and the HCCI transition layer under constitutional undercooling. A large amount of C and Cr, and a small amount of Si and Mn dissolve in the matrix. Granular Cr_7C_3 is uniformly distributed. Due to the solute redistribution at the solid-liquid interface, the primary austenite grows from planar to cellular and finally to the distinct dendrite crystals. The dendrite crystals have an obvious growth direction perpendicular to the composite layer.

Experimental research on electromagnetic continuous casting high-speed steel composite roll

A high speed steel composite roll billet was fabricated, which is regular in shape, smooth in surface, slight in trace, compact in internal structure, free of slag inclusion, shrinkage cavity, cracks and other flaws, and good in macro quality of junction surface using a vertical continuous casting machine. The interface zone microstructure of bimetallic in billet of high speed steel composite roll was analyzed by metallurgical microscope(OM), X-ray diffractmeter(XRD), scanning electron microscopy(SEM) and energy-dispersive X-ray analysis(EDS). The results indicate that the microstructure of roll billet is composed of chilled solidified layer, dendrite zone, interfacial zone of bimetal and core material zone. The microstructure of outer shell material is composed of martensite + bainite + residual austenite + some small labyrinth-shape, small-short lath-shape, or dollop-shape eutectic carbides. The microstructure of core material is slice-shape pearlite and a little ferrite along boundary of cells. The interface region microstructure of bimetallic composite roll consists of diffusion region, chilled solidified layer and columnar grain region.

Preparation of Composite Particles by Forming Pickering Emulsion Followed by Drying-In-Liquid and Effect of Stepwise Addition of Solid Powder on Structure of Composite Particles

It was tried to prepare composite particles made of polymer and two kinds of solid powders by forming Pickeringemulsion followed by the drying-in-liquid method and to investigate how the stepwise addition of solid powders affected the contained ratio and adhesion ratio of solid powders and the structure of composite particles. Limonene oil dissolving expanded polystyrene and ethylene glycol were adopted as the dispersed phase and the continuous phase, respectively. Magnetite and titanium dioxide were used as solid powders. Magnetite was added before or after formation of the (O/W) dispersion. Titanium dioxide was added at the various elapsed times from addition of magnetite. Titanium dioxide adhered only on the surface of composite particles irrespective of addition time. At the earlier addition of both solid powders, the surface-covering type composite particles were prepared. At the latter addition of titanium dioxide, a part of magnetite adhered on the surface and the remainder was dispersed into composite particle.

65Mn/Q235双金属复合管的热处理工艺优化及其耐磨性

采用金相显微镜、扫描电子显微镜、洛氏硬度计、显微硬度计和磨粒磨损试验机,分析了65Mn/Q235双金属复合管在使用过程中失效的原因,并对其热处理工艺进行了优化。结果表明:65Mn钢中存在大量的未溶碳化物和层片状珠光体,导致其韧性降低、焊缝硬度较低,使65Mn/Q235双金属复合管在服役过程中因耐磨性不足而失效。采用优化的热处理工艺即840℃保温10~30 min油冷后,65Mn/Q235双金属复合管的组织为均匀细小的马氏体,未溶碳化物和层片状珠光体基本消除,焊缝硬度得到提高,耐磨性明显改善。

增材制造钛基金字塔点阵结构对镁/钛双金属复合材料界面强化的优化

采用超声辅助固-液复合铸造的方法,通过在界面处采用增材制造的钛基金字塔型点阵材料制备镁/钛异种双金属复合材料。采用正交法对点阵结构参数进行优化。结果表明,优化后的点阵结构参数为:杆直径(d)1 mm,杆长与杆直径比(l/d)3,上节点和下节点直径与杆直径比(d_(1)/d,d_(2)/d)均为2.5,其中l/dd是影响接头失效强度的最显著因素,最优点阵结构参数下镁/钛双金属接头的失效强度为77.3 MPa。实验结果和有限元分析表明:随着点阵结构长径比的增加,镁/钛双金属接头的失效强度先增加后减小,当长径比为3时,失效强度达到最大。

钢/铝双金属固-液复合工艺研究

研究冲击射流固-液复合法制备钢/铝复合材料,预先对钢基体表面预处理,在浇铸过程中改变钢基体的移动速度,使得铝液与钢基体产生不同程度强化换热作用。利用SEM、XRD、EDS及导热仪检测分析钢/铝复合层的组织形貌、成分及导热性,用万能力学试验机测量其剪切强度。实验结果表明,随着钢基体移动速度升高,铝液对钢基体冲击射流换热量减小,复合界面由Fe/Al金属间化合物组成,钢基体表面镀锌层起到了润湿、漫流、保护作用,有效提升了钢/铝之间结合强度。在浇铸温度810℃,钢基体移动速度为12 mm/s时,测得结合强度为19.1 MPa,测得最高热导率为88.23 W/(m·K)。

超声施振方式对消失模铸造Al/Mg双金属复合材料界面组织和力学性能的影响

研究了连续超声振动和间歇超声振动两种施振方式对消失模铸造Al/Mg双金属材料界面组织和力学性能的影响。结果表明,未施加超声振动Al/Mg双金属界面由Al-Mg金属间化合物区和共晶组织区组成,两个区域边界存在一层氧化膜,阻碍了元素扩散,Mg_(2)Si相呈网状,团聚分布于金属间化合物区。两种超声施振方式均能通过超声空化效应和声流效应破碎和消除氧化膜,并使Mg_(2)Si相细化和分散于整个界面,部分共晶组织转变为金属间化合物,提高了界面组织和显微硬度分布均匀性。连续超声振动作用下Al/Mg双金属界面剪切强度达到53.9 MPa,相比未超声处理提升63.8%。间歇超声振动作用下,界面厚度较连续超声振动减小,然而局部区域存在孔洞缺陷和Mg_(2)Si相局部聚集,削弱了对界面的强化效果,但界面剪切强度仍达到49.5 MPa。

科研实验融入材料成型及控制工程专业教学实践——双金属复合材料制备及分析

设计了一个基于双金属固-液熔铸法的钆/铜功能复合材料制备实验,并采用现代材料分析技术对钆/铜界面结合形貌进行观测和分析。通过将科研项目实验融入专业实践应用教学,学生可以锻炼材料制备成型和分析的能力,熟悉稀土金属钆和铜的反应特性,掌握熔铸复合成型设备、扫描电镜和金相显微镜的使用和分析方法,获得具有良好结合界面的双金属功能复合材料及其工艺参数,巩固所学专业知识,了解科学前沿,培养工匠精神,提升综合应用能力和科学素养。

825衬里双金属复合管层间与焊缝的电化学腐蚀行为

采用三电极体系对825衬里双金属复合管进行电化学测试,得到了层间三个不同界面及焊缝四个不同界面的极化曲线与电化学阻抗谱。结果表明:层间区域X65界面的腐蚀倾向最大,焊缝区域三种混合界面的腐蚀倾向最大。

离心浇铸复合机筒双金属层开裂原因

在对某高强度离心浇铸复合机筒进行成品检测过程中,发现多件机筒的双金属层开裂。采用低倍组织检验、化学成分分析、金相检验等方法,并结合工艺分析,研究了复合机筒开裂的原因。结果表明:复合机筒的双金属层有疏松缺陷,在压力的作用下,机筒发生开裂;机筒产生疏松缺陷的原因为离心浇铸加热温度不足、保温时间较短、使用的硼砂质量较差等。

热双金属复合材料的研究现状与展望

热双金属复合材料是一种利用先进复合技术,使两种及以上具有不同热膨胀系数的金属复合形成冶金结合的层状复合材料。该材料可发挥不同金属的自身性能优势,实现复合材料的性能互补,同时因其形状可随环境温度改变而调控的特性,被广泛应用于电子电器领域。随着电子科学技术飞速发展,对热双金属产品品质的要求也日益提高,总结并展望该材料在该领域的研究现状与前景意义重大。围绕电子电器领域的热双金属复合材料,综述了其制备原理、特性、组元构成、主要性能指标和制造技术。热双金属复合材料的工作原理是通过复合技术将两种及以上的金属层交替叠加并紧密结合,由于不同金属各异的热膨胀系数,当通过环境传导或自我发热方式受到热力刺激时,整个材料发生弹性弯曲变形而发生形状变化。热双金属的组元构成是影响其性能的重要因素,选择合适的金属组元可以使其具备更优异的性能。常见的组元包括钢-铝、铜-铝等,高膨胀层一般为锰铜合金,低膨胀层一般为铁镍合金。通过合理设计不同金属的层厚比例和堆叠顺序,可以调控材料的热膨胀性能和机械强度,主要性能指标包括材料的热膨胀系数、电导率和机械强度等,其中热膨胀系数决定了材料在不同温度下的形状变化程度,电导率影响了材料在电子电器中的导电性能,而机械强度则直接关系到材料的使用寿命和稳定性。制造技术是影响热双金属复合材料品质的关键因素之一,常见的制造技术包括爆炸复合、轧制复合和粉末冶金等。不同的制造技术会影响材料的结合程度、微观结构及性能稳定性,因此在选择制造技术时需要考虑到具体的应用场景和要求。最后,对热双金属复合材料未来的主要发展方向进行了展望。

液氨储运用钢研究进展及展望

在“双碳”政策背景下,以氨为载体的能源利用形式具有巨大发展前景。中国氨的应用领域广泛,其相关的技术较成熟,液氨需求量也在逐年增长。然而,中国在液氨长输管道的建设上仍有很大的发展空间。由于中国工艺技术水平、产品类别与产量、储运地理条件、气候环境和使用条件等因素,开发适合中国国情实际的氨储运新材料具有必要性、经济性与前瞻性。借鉴国外成熟产品与技术,通过调整合金元素成分、采用微合金化技术以及应用双金属复合管技术,开发高强度、高韧性以及抗腐蚀性能的氨/液氨专用输送管线钢、储罐用钢和耐高温钢,可实现氨/液氨储运用钢的细化与专业化,增加不同用途材料的类型数量。

液态模锻双金属复合锤头模具设计

为了提高破碎机双金属复合锤头的综合性能,延长其使用寿命,本文提出了采用液态模锻工艺生产双金属复合锤头的方案,并进行了相应的模具设计。模具采用直立位直接加压液锻成型,可替换模芯,垂直分模,下缸上行顶出的方案。

重油加氢螺纹锁紧环换热器应用及运维策略

高压换热器是重油加氢裂化装置的核心设备之一,以螺纹锁紧环高压换热器应用最广。直径在φ1 600 mm以上者即为大口径高压换热器,该类换热器在国内部分炼油装置中出现过内漏情况。发生原因主要为内件和壳体膨胀差不同导致的,需要通过升级垫片和做好检修控制保证高压螺纹锁紧环换热器不发生内漏。

Research on continuous core-filling casting forming process of copper-clad aluminum bimetal composite material

A single forming equipment of bimetal continuous core-filling casting was designed and manufactured for the purpose of developing copper-aluminum composite materials.The characteristics of the equipment were as follows：the crystallizer composed of water jacket copper sleeve in which graphite sleeve was set, two melting furnaces with different diameters vertically distributed, the low furnace of melting copper linked with the crystallizer, continuous casting and core-filling proceeded at the meantime.The rational processing parameters were determined through a series of experiments：contact length from down crucible to water-cooling cupreous crystallizer, 20 mm;length of recooling spray jet under crystallizer, 95 mm;temperature of copper and aluminum, 1250-1320℃ and 700℃ respectively;pulling rate, 16 mm/min.The qualified copper-clad aluminum composite rods, the external and inner diameter of which was 40 mm and 24 mm respectively, could be drawn successfully on that basis.Tested by hydrostatic extrusion and drawing process, the boss ratios of the copperclad aluminum composite rods were maintained a relatively stable scope of about 0.59-0.65, which was not obviously changed by subsequent plastic processing.

油气改造平台双金属复合钢管施工技术应用

双金属复合钢管具有良好的耐腐蚀性、表面光洁度高、抗拉伸强度高、耐高温性、优越的韧性等优点,被广泛应用于海上油气平台。其中在改造平台方面海上施工设备及工艺方法的选择相比于陆地预制更加困难,这也是海上油气改造平台顺利投产的关键点。