活性填料对聚硅氮烷连接SiC陶瓷接头性能的影响

采用陶瓷先驱体聚合物--含乙烯基聚硅氮烷并加入活性填料纳米铝粉连接无压烧结SiC陶瓷.研究了纳米铝粉填料对连接强度的影响,并对连接层的微观结构及成分进行了分析.结果表明,纳米铝粉的加入,促进了聚硅氮烷的裂解,降低了连接温度,减少了连接层内的孔隙等缺陷,从而有效地提高了连接强度.当连接温度为1 150 ℃,加入纳米铝粉填料所获得的连接件经2次浸渍/裂解增强处理后,其室温三点抗弯强度达到最大值为146.8 MPa.XRD分析表明,连接层含有Si3N4,SiC及少量AlN等微粒.微观结构及成分分析显示,连接层厚度约为5 μm,元素分布较为均匀,连接层与母材之间接合良好.     

采用新型聚硅氮烷连接无压烧结SiC陶瓷

采用新型陶瓷先驱体聚合物-含乙烯基聚硅氮烷(PSZ)连接无压烧结SiC陶瓷.研究了PSZ的裂解过程以及连接温度、浸渍/裂解增强处理、惰性填料对连接强度的影响,并对连接区域微观结构进行了分析.结果表明,在1200～1400℃温度范围内,PSZ的裂解产物发生了由非晶态向晶态的转变.随着连接温度的升高,连接强度先升高后降低;浸渍/裂解增强处理可较大幅度提高接头强度;另外加入适量的纳米SiC填料可有效提高连接强度.当连接温度为1300℃,纳米SiC填料(质量分数)为5%时,经三次增强处理的连接件接头剪切强度达33.5 MPa.微观结构分析显示,连接层厚度约为3～4 μm,连接层与母材之间界面接合良好.     

采用SiC/Si_3N_4陶瓷先驱体连接反应烧结SiC

采用SiC/Si3N4陶瓷先驱体聚硅氮烷连接反应烧结碳化硅陶瓷,研究了连接温度、连接压力、浸渍/裂解增强处理对连接强度的影响。结果表明:在1100℃~1400℃温度范围内,连接强度先升高后降低;连接过程中施加适当的轴向压力可提高连接层致密度;浸渍/裂解增强处理可大幅度提高接头强度。当连接温度为1300℃,连接压力为15kPa,经3次增强处理的连接件抗弯强度达最大值169.1MPa。这种连接件的断口表面粘有大量SiC母材。由XRD研究表明,随着温度的逐步升高,聚硅氮烷的裂解产物发生了由非晶态向晶态的转变。微观结构及成分分析显示:连接层为厚度2μm~3μm的SiCN无定形陶瓷,其结构较为均匀致密;连接层与基体间界面接合良好。     

陶瓷先驱体聚硅氮烷连接Cf/SiC工艺及连接性能

采用陶瓷先驱体转化法连接Cf／SiC复合材料。针对Cf／SiC复合材料的不同连接界面特性,采用不同的连接配方和工艺。结果表明：对于第一类以SiC相为主的连接界面,采用单一的聚硅氮烷即可实现Cf／SiC复合材料的连接,当连接温度为1300℃,经两次浸渍／裂解增强处理的连接件接头抗剪强度达最大值29．6MPa;连接层厚度为2～3μm,其结构较为均匀致密,由无定型SiNC陶瓷组成;对于第二类以C纤维端面为主的连接界面,采用聚硅氮烷并加入活性填料纳米Al粉来实现其连接：当连接温度为1150℃,经两次浸渍／裂解增强处理的连接件抗剪强度达最大值22．5MPa;连接层厚度约为30μm,连接层中含有SiC、Si3N4和AlN等相。     

采用SiC/Si3N4陶瓷先驱体连接反应烧结SiC

采用SiC/Si3N4陶瓷先驱体聚硅氮烷连接反应烧结碳化硅陶瓷,研究了连接温度、连接压力、浸渍/裂解增强处理对连接强度的影响.结果表明：在1100℃～1400℃温度范围内,连接强度先升高后降低;连接过程中施加适当的轴向压力可提高连接层致密度;浸渍/裂解增强处理可大幅度提高接头强度.当连接温度为1300℃,连接压力为15kPa，经3次增强处理的连接件抗弯强度达最大值169．1MPa。这种连接件的断口表面粘有大量SiC母材。由XRD研究表明，随着温度的逐步升高，聚硅氮烷的裂解产物发生了由非晶态向晶态的转变。微观结构及成分分析显示：连接层为厚度2μm-3μm的SiCN无定形陶瓷，其结构较为均匀致密；连接层与基体间界面接合良好。     

重复浸渍裂解先驱体高温连接Cf/SiC陶瓷基复合材料

对先驱体硅树脂高温(1200℃)转化陶瓷接头连接Cf/SiC复合材料进行了研究.探讨了添加活性填料(纳米级Si,Al粉)后先驱体裂解所发生的反应趋势及重复浸渍-裂解过程对连接强度的影响.结果表明,通过添加活性填料纳米级Si,Al粉可以改善连接效果,但性能难以达到应用目标.通过重复浸渍2 g/mLSR249/ethanol溶液-裂解可以提高连接剪切强度.经过8个浸渍-裂解周期后,得到连接剪切强度达到64.24 MPa.     

活性填料控制的先驱体裂解陶瓷的尺寸变化

对单一先驱体、先驱体／惰性填料、先驱体／活性填料体系裂解陶瓷的尺寸变化进行了模型分析。从理论上分析了活性填料体积分数与裂解陶瓷体积收缩率和线收缩率之间的关系，揭示了活性填料的临界体积分数与活性填料反应的产率、反应前后的密度比之间的相关性，以聚碳硅烷先驱体为例，预测了在不同反应情况下，常见活性填料的临界体积分数，增加活性填料体积分数，可降低陶瓷产物的体积收缩率和气孔率。     

采用Ni-Cr-Nb焊料连接再结晶SiC陶瓷

采用Ni-Cr-Nb(Ni-Cr-Nb的质量比为47.5:49.5:3)焊料连接再结晶SiC陶瓷.正交试验的结果表明,连接温度对接头强度的影响最大,保温时间的影响次之,焊料理论厚度对接头强度的影响最小.最佳工艺参数为:连接温度1400℃、保温时间10 min、焊料理论厚度为480 μm.在此工艺条件下进行连接试验,接头的三点抗弯强度为75.1 MPa,为再结晶SiC陶瓷母材强度的57.8%.断口类型为混合断口,一部分位于连接层,一部分位于SiC陶瓷母材.微观结构研究表明,Ni、Cr和Nb元素与SiC陶瓷母材中的Si和C元素发生了互扩散,形成了反应层和中间层,中间层主要由NbC、Ni2Si和CrsSi3等组成.     

聚硅氧烷连接RBSiC陶瓷

采用陶瓷先驱体有机聚合物聚硅氧烷连接反应烧结碳化硅（RBSiC）陶瓷。研究了连接温度、连接压力、保温时间对连接强度的影响。通过正交优选实验，确定了最佳工艺参数：连接温度为1300℃，连接压力为25kPa，保温时间为120min。在此工艺条件下制备的连接件经3次浸渍／裂解增强处理，其抗弯强度达132．6MPa，连接件断口表面粘有大量从母材剥离下来的SiC。XRD研究表明，在1100℃～1400℃的试验范围之内，随着连接温度的逐步升高，聚硅氧烷的裂解产物发生了由非晶态向晶态的转变。这种转变对连接强度有显著影响。扫描电镜（SEM）及能谱（EDX）分析显示，连接层厚度为3μm左右，结构较为均匀致密，且与母材间界面结合良好。     

钛粉在聚硅氮烷裂解制备陶瓷材料中的应用

采用IR、TG、XRD等手段研究分析钛粉作为活性填料在聚硅氮烷裂解制备陶瓷材料中的应用。实验表明：钛粉可以有效改善先驱体的陶瓷产率,本实验中纯PSN-1先驱体在经1300 ℃裂解陶瓷产率仅为37.3%,通过加入质量比3/10（Ti/PSN-1）的钛粉,经1300 ℃裂解陶瓷产率为78.7%,提高了约40%;经红外光谱分析表明,通过向先驱体中加入Ti粉可以加速有机先驱体向无机陶瓷转化的速度;经X衍射分析表明,Ti粉作为活性填料能与先驱体裂解挥发份及保护气氛发生反应,生成TiC、TiN等新的物相,有利于提高陶瓷产率。     

金属基复合材料连接方法研究综述

拥有良好综合性能的金属基复合材料的应用往往受到没有成熟连接方法的限制。为解决这个问题, 本文对各种连接金属基复合材料的方法进行了系统阐述,并分析其各自的应用场合和限制条件,以便读者进行复合材料连接工艺选择时参考。     

金属基复合材料连接方法研究综述

拥有良好综合性能的金属基复合材料的应用往往受到没有成熟连接方法的限制。为解决这个问题，本文对各种连接金属基复合材料的方法进行了系统阐述，并分析其各自的应用场合和限制条件，以便读者进行复合材料连接工艺选择时参考。     

Characteristics of deformation joining of aluminum-stainless steel composite sheet

1　INTRODUCTIONAseveryoneknows ,aluminumandstainlesssteelaredifficulttoweldtogether[16 ] .Inthepast,braz ing ,projectionweldingaswellasaluminizingwereused .Nowadays ,anewmethodisputforward ,inwhichthealuminumsheetandstainlesssteelsheetheatedbyinductionheaterareconnectedbypressureofascrew press .Notonlycanthismethodimprovebondingbehaviorofthecompositesheet,butalsocanitraisetheproductivity greatly .Thistechnologyiscalleddeformationjoining ,i.e .pressjoining .InChi na ,ithasbeensuccessfully…     

SiC陶瓷连接工艺及焊料反应产物研究

采用热压反应烧结技术，使用Ti-Ni混合金属粉末焊料对SiC陶瓷进行连接，探讨了焊接温度、保温时间、焊料厚度以及焊接压力等工艺参数对连接件抗弯强度的影响规律，并通过对连接界面及焊料反应产物进行SEM，EDS，XRD分析，进一步考察了焊接工艺对连接件的断裂类型，焊料反应产物及其结合强度的影响规律。结果表明，采用适当的连接工艺，Ti-Ni焊料与母材可通过适当且适度的界面反应获得牢固结合，此时界面反应产物为以TiC,NiTi为主含Ni3C,Ni16Ti6Si7的混合物，且具有较高强度的TiC以弥散相形式分布在以具有一定韧性的金属间化合物NiTi为主的基质中，对接头性能的改善起到关键作用。在本实验范围内，在连接温度1100摄氏度，保温时间20min，焊接压力12．7MPa，焊料厚度0．3mm条件下可获得最佳陶瓷接头，其相对抗弯强度为53％。     

Direct dissimilar joining of aluminium alloys and polyamide 6 by friction lap joining*

Direct dissimilar joining of various Al alloy (A1050, A3004, A5052 and A5083) plates and a polyamide 6 plate was performed using friction lap joining (FLJ) with the Al alloy plate as a top and the polyamide 6 plate as a bottom. The effect of Mg content in Al alloys on the joining strength was investigated. TEM analysis made clear that the polyamide 6 and Al alloys were joined via oxide layer consisting of Al₂O₃ and MgO. The results of XPS analysis indicated that MgO was formed by the heating during FLJ, and the quantity of MgO was increased with increasing Mg content in Al alloys. The tensile shear strengths of A3004, A5052 and A5083 joints were saturated to about 2 kN because of the tensile fracture at the polyamide 6 plate outside the tool-passed zone, which were higher than that of the A1050 joint fractured at the joint interface. The peel strength of the joint was increased with increasing Mg content in Al alloys, and the fracture occurred both at the joint interface and at the polyamide 6 plate on the joint area. The fraction of polyamide 6 plate fracture was also increased with increasing Mg content in Al alloys.     

Application of a Uniform Pressure Actuator for Electromagnetic Processing of Sheet Metal

High-velocity electromagnetic sheet-metal forming and processing has many potential advantages over more conventional techniques, including: higher-forming limits, resistance to wrinkling and springback, one-sided tooling, and physical contact to only one side of the work piece. Traditional electromagnetic actuators are flat spirals that produce a nonuniform pressure distribution, limiting the types of parts that can be formed. A new type of electromagnetic actuator, the uniform pressure (UP) actuator, has been developed. The UP actuator can uniformly and efficiently accelerate conductive sheet metal to velocities on the order of 200 m/s or greater over distances of a few millimeters. When the material is arrested by impact with a tool, high-forming pressures can be imparted to it. The utility of the UP actuator is illustrated here by demonstrating its ability to form sheet metal components with intricate shape, to shock harden, and also to pick up nearly arbitrarily small details from a die surface. Thus, electromagnetic processing with the use of the UP actuator offers the unprecedented ability to simultaneously form and engineer the surface morphology and microstructure of sheet metal samples. This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati, OH, October 15-19, 2006.     

汽车金属板件压接工艺研究

压接工艺是一种金属板件机械连接新技术。本文结合实际的工艺试验研究工作,重点介绍了压接工艺的方法,压接工艺的原理及金属流动过程,压接连接的强度特性,以及有关汽车零件的实际应用情况。     

Fluxless arc weld-brazing of aluminium alloy to steel

In this work, joining of aluminium alloy AA6061-T6 to Interstitial Free steel using pulsed gas metal arc welding process has been attempted. The effect of different surface conditions of steel (viz, galvanized, galvanealed and uncoated) and gap between the sheets on braze joint formation have been investigated. Galvanized steel surface showed good bead width, joint formation and lap shear strength compared to the other two combinations. Interface gap has not affected the wetting behaviour significantly but presence of a gap of 300 μm or so helped in escape of zinc vapour during the process there by avoiding formation of any crevice or macroporosity in the joint. Features and properties of the joint are characterized by metallography, fractography, energy dispersive spectroscopy (EDS) and lap shear tests. Load carrying capacity of Al-Galvanized steel was highest (222 N/mm of seam length) compared to other combinations, aided by better wetting due to presence of Zn on the surface and minimum porosity due to interfacial gap provided during brazing.     

Effect of silane coupling on the joint characteristics of friction lap joined Al alloy/CFRP

Dissimilar materials joining of an A5052 plate and a carbon fibre reinforced thermoplastic (CFRTP), which consisted of polyamide 6 (PA6) with 20 wt% carbon fibre addition, was performed using friction lap joining (FLJ) with the Al alloy plate as a top and the CFRTP plate as a bottom. The joint characteristics were evaluated to investigate effects of the surface treatment by the silane coupling treatment for A5052 and the joining speed on the joining properties. The joint strength was increased by inducing the silane coupling treatment for the A5052 plate surface. The tensile shear fracture load of the silane coupling treated FLJ joint increased by increasing the joining speed up to 6.67 mm/s and then decreased. The maximum tensile shear fracture load of 5.0 kN was obtained at the joining speed of 6.67 mm/s, and the fracture occurred at the CFRTP base plate with the joint efficiency of 97%. The shear strength of the joint interface of the joint formed at the joining speed of 1.67 mm/s, which fractured at the joining interface by the tensile shear test, was estimated to be about 19 MPa. The covalent bondings between the A5052 plate and the silane coupling layer, and the silane coupling layer and the CFRTP plate were indicated by inducing the silane coupling treatment.