铜合金表面渗铝工艺研究

利用粉末包埋法对低铝铜合金表面进行渗铝,考察不同的密封性、温度、时间对渗铝层的影响,结果表明:用管式容器在900 ～950℃进行渗铝,保温6～8h,可以获得170 ～200 μm左右的渗铝层.经SEM观察,发现渗铝层厚度非常均匀,与基体有明显的界面,界面结合良好,渗层组织较基体致密.利用阿累尼乌斯经验公式求得铝的扩散激活能为103.69 kJ/mol.     

AgCuTi钎焊炭/炭复合材料的组织结构

采用Ag-Cu-Ti钎料连接C/C复合材料,用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等分析连接层的微观结构与相组成,并测试连接层的剪切强度。结果表明:C/C复合材料连接层的剪切强度跟连接温度与保温时间有关;在850℃、保温30 min条件下获得的连接层剪切强度最高,达到26.7 MPa;同时连接层与基体材料形成机械嵌合,界面发生元素扩散和冶金反应。钎焊连接层形成固溶体和化合物,包括Ag(s.s)、Cu(s.s)、Cu4Ti3和TiC。剪切断口形貌表明钎焊层与C/C坯体之间结合较好,具有一定的连接强度。     

玻璃与铝阳极键合中残余应力有限元分析

叙述了玻璃与铝阳极键合试件冷却过程的应力有限元分析方法,获得了键合件从450℃冷却到室温后,键合件内的应力分布信息。     

等离子喷涂Mo包覆Ni20Cr自粘结粉末制备的粘结层结合性能

针对如何提升金属粘结层结合强度的问题,本研究提出了使用Mo包覆Ni20Cr复合粉末作为新型粘结层材料的方法。高熔点Mo包覆层可以减少喷涂过程中核芯元素的蒸发,在大气等离子喷涂条件下获得超高温熔滴,有助于涂层与基体以及涂层内部实现冶金结合。采用机械合金化法制备了Mo包覆Ni20Cr复合粉末,并在大气等离子喷涂条件下制备涂层考察其结合强度。通过一维传热模型预测了镍基合金熔滴碰撞在镍基合金、奥氏体不锈钢和低碳钢基体上实现铺展熔合冶金自结合所需要的温度,采用DPV-2000测试系统对粒子飞行过程中的温度进行测量,使用扫描电子显微镜(SEM)对涂层的微观结构进行了表征。粒子温度测量结果表明,在大气等离子喷涂条件下,Ni20Cr-Mo熔滴可加热至2620℃以上,满足碰撞铺展过程中引起基体表面熔化而产生冶金结合的温度条件。涂层结合强度拉伸试验中所有试样都从胶中断裂,涂层结合强度大于76.1 MPa。组织观察结果表明涂层组织结构致密,不仅大量粒子层界面间产生了冶金结合,涂层与基体界面处也观察到一定深度的熔坑,表明涂层与基体以及涂层层间界面均实现了冶金结合,由此显著提高了结合强度。     

AZ31/1060爆炸复合板界面区组织与性能研究

爆炸焊接是应用爆炸载荷使基板和复板面复合的固相连接技术,将镁合金和纯铝复合形成层状复合材料有望拓宽镁合金的应用。本文通过爆炸焊接成功地实现了AZ31镁合金和1060纯铝的面复合,应用光学显微镜(OM),扫描电镜(SEM),透射电镜(TEM)及电子式万能试验机和维氏硬度计对AZ31/1060结合界面处的显微组织、成分分布、力学性能进行测试和分析。结果表明,应用爆炸焊接技术可以使AZ31镁合金和1060纯铝的焊合率达到99.4%;结合界面成波形结构,爆炸焊接过程中,界面处发生元素扩散;随着到界面距离的增加,镁合金的显微组织逐渐从形变带过渡到细晶区再转变为拉长晶粒区,远离界面的组织以等轴晶为主;AZ31/1060爆炸复合板抗拉强度为175 MPa,延伸率为3.3%,剪切强度为62.2 MPa,在拉伸断裂过程中镁合金先断裂然后纯铝断裂,结合界面处不发生开裂;界面处镁合金一侧存在高硬度区,厚度约为200μm。     

SiCf/TC11复合材料拉伸行为研究

采用磁控溅射先驱丝法和热等静压工艺制备SiC_f/TC11复合材料，研究了SiC_f/TC11复合材料室温和500℃拉伸性能及断裂机制。结果表明，SiC_f/TC11复合材料室温和500℃抗拉强度分别为1 530 MPa和1 553 MPa，明显高于基体TC11钛合金，与TC11钛合金相比，抗拉强度分别提升了～57%和～133%，纤维增强效果显著。通过观察SiC_f/TC11复合材料室温、500℃拉伸断口和纵剖面断裂特征，指出了室温和500℃拉伸断裂机制主要包括反应层多次断裂、纤维一次断裂、纤维多次断裂、纤维-基体界面脱粘、纤维拔出、W芯-SiC界面脱粘、基体断裂、包套断裂等，揭示了SiC_f/TC11复合材料室温和500℃拉伸载荷下多组元失效断裂过程。     

热轧7075/AZ31B复合板的显微组织及结合性能

为了研究热轧铝/镁复合板结合强度的变化规律,本文综合考虑压下率、轧制温度和轧制速度等多种轧制参数,单道次热轧制备了7075 Al/AZ31B Mg复合板。结果表明:在复合板轧制过程中由于热和强变形作用组织发生了动态再结晶,且增大轧制速度有助于镁基体产生完全动态再结晶。在相同轧制温度下,铝镁复合板结合强度均随压下率增加先升高后降低;强度升高是由于界面元素扩散宽度的增大和镁合金近界面晶粒组织的细化所致,强度降低是由于大变形导致镁基体近界面处产生裂缝,以及塑性功产生热量过多使得镁基体温度升高导致的镁侧晶粒长大所致。对复合板进行拉剪实验,铝镁结合界面剪切强度较低时,断裂发生在复合界面处且成脆性断裂特征,强度较高时断口形貌呈韧性断裂特征,断裂发生在镁基体侧。      

3D封装用Cu/Sn/Cu焊点的组织与剪切性能研究

研究了250℃温度,不同键合时间对Cu/Sn/Cu焊点的界面金属间化合物(intermetallic compound,IMC)生长行为及剪切性能的影响。结果表明:键合时间由30 min增加到120 min,Cu/Sn/Cu焊点界面IMC的厚度逐渐变厚。当键合时间为30 min时,焊点界面IMC厚度为12. 8μm。随着时间增加到120 min,焊点中的液相Sn消耗殆尽,形成了全IMC。在Cu/Sn/Cu焊点中,发现焊点两端界面IMC呈现非对称生长。键合时间为30 min时,焊点界面Cu_3Sn的厚度分别为1. 73μm(冷端)和0. 95μm(热端),冷端IMC的增长速率明显高于热端,主要原因归结于温度梯度。通过对焊点界面IMC进行电子背散射衍射(EBSD)分析,发现存在的大块晶粒组织为Cu_6Sn_5,而Cu_3Sn的晶粒相对较小。根据横截面方向(transverse direction,TD)反极图显示,Cu_6Sn_5的晶粒取向多平行于[001]与[111]之间。此外,随着键合时间的增加,焊点的剪切强度不断增加,当键合时间为120 min时,焊点的剪切强度由8. 5 MPa增加到18. 6 MPa,焊点的断裂模式由初始的混合断裂逐渐转变为脆性断裂。     

铝与玻璃的阳极键合

介绍了玻璃与铝阳极键合原理、工艺特点、影响因素,给出了最佳工艺参数。     

铝与玻璃的阳极键合

本文简要介绍了玻璃与铝阳极键合原理、工艺特点、影响因素,给出了最佳工艺参数。     

Bonding of Silicon Nitride Ceramic Composite with RE_2O_3Al_2O_3SiO_2 Glass Solders

Ｓｉｌｉｃｏｎｎｉｔｒｉｄｅｃｅｒａｍｉｃｈａｓａｓｅｒｉｅｓｏｆｅｘｃｅｌｌｅｎｔｐｒｏｐｅｒｔｉｅｓ,ｆｏｒｅｘａｍｐｌｅ,ｈｉｇｈｓｔｒｅｎｇｔｈ,ｈｉｇｈｈａｒｄｎｅｓｓ,ｗｅａｒ,ｃｏｒｒｏｓｉｏｎ,ｏｘｉｄａｔｉｏｎａｎｄｓｈｏｃｋｒｅｓｉｓｔａｎｃｅｅｔｃ．,ａｎｄｉｓａｋｉｎｄｏｆｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｔｒｕｃｔｕｒａｌｍａｔｅｒｉａｌｗｉｔｈｅｎｏｒｍｏｕｓｐｏｔｅｎｔｉａｌｉｔｉｅｓｆｏｒｆｕｔｕｒｅｄｅｖｅｌｏｐｍｅｎｔ．Ｂｕｔｈｉｇｈｃｏｓｔｆｏｒ…     

镀层对金刚石/玻璃复合材料性能的影响

为满足现代电子工业日益增长的散热需求,急需研究和开发新型高导热陶瓷（玻璃）基复合材料,而改善复合材料中增强相与基体的界面结合状况是提高复合材料热导率的重要途径.本文在对金刚石和镀Cr金刚石进行镀Cu和控制氧化的基础上,利用放电等离子烧结方法制备了不同的金刚石增强玻璃基复合材料,并观察了其微观形貌和界面结合状况,测定了复合材料的热导率.实验结果表明:复合材料中金刚石颗粒均匀分布于玻璃基体中,Cu/金刚石界面和Cr/Cu界面分别是两种复合材料中结合最弱的界面;复合材料的热导率随着金刚石体积分数的增加而增加;金刚石/玻璃复合材料的热导率随着镀Cu层厚度的增加而降低,由于镀Cr层实现了与金刚石的化学结合以及Cr在Cu层中的扩散,镀Cr金刚石/玻璃复合材料的热导率随着镀Cu层厚度的增加而增加.当金刚石粒径为100μm、体积分数为70%及镀Cu层厚度为约1.59μm时,复合材料的热导率最高达到约91.0 W·m-1·K-1.      

Effect of the Fourth Element on Bonding of Silicon Nitride Ceramics with Y_2O_3-Al_2O_3-SiO_2 Glass Solders

Ｂｏｎｄｉｎｇｏｆｓｉｌｉｃｏｎｎｉｔｒｉｄｅｃｅｒａｍｉｃｓｗｉｔｈｏｘｉｄｅｇｌａｓｓｓｏｌｄｅｒｈａｓｂｅｅｎａｃｈｉｅｖｅｄｖｅｒｙｇｒｅａｔｓｕｃｃｅｓｓ[1～ 11] .Ｏｗｉｎｇｔｏｔｈｅｌｏｗｅｒｓｏｆｔｅｎｉｎｇｔｅｍｐｅｒａｔｕｒｅｏｆｒｅｓｉｄｕａｌｇｌａｓｓｉｎｊｏｉｎｔ ,ｔｈｅｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｔｒｅｎｇｔｈｏｆｊｏｉｎｔｈａｓｂｅｅｎｄｅｔｅｒｉｏ ｒａｔｅｄ .Ｉｎｏｒｄｅｒｔｏｉｍｐｒｏｖｅｔｈｅｊｏｉｎｔｓｔｒｅｎｇｔｈａｔｅｌｅｖａｔｅｄｔｅｍｐｅｒａｔｕ…     

Resin-modified glass ionomers for luting posterior ceramic restorations

OBJECTIVES: Until recently, esthetic inlay restorations in posterior teeth have been limited to cavities surrounded by enamel. Dentin adhesive systems in combination with luting composites and light-cured resin-modified glass ionomer cements offer a possibility for bonding ceramic inlays to cavities when the cervical margin is in dentin. This study was designed to compare in vitro marginal integrity of ceramic inlays bonded to dentin to restorations placed in cavities with margins located entirely in the enamel. METHODS: In the present in vitro study, the sealing abilities of a dentin bonding agent/luting composite combination (Syntac/Dual Cement, Vivadent) and resin-modified glass ionomers (Photac Fil, Photac Bond, ESPE; Dyract, De Trey Dentsply; Fuji II LC, GC Dental Industrial Corp.; and Vitremer, 3M Dental Products) used as luting agents in cavities extending beyond the cemento-enamel junction, were compared to the sealing abilities of a conventional luting composite (Vita Cerec Duo Cement, Vita) in cavities within sound enamel. SEM analysis and dye penetration were performed to evaluate marginal integrity at the cervical cavity margins. RESULTS: The dentin bonding agent/luting composite combination (Syntac/Dual Cement) rendered a marginal seal within the dentin similar to the quality obtained with the conventional luting procedures within sound enamel. When three out of the five resin-modified glass ionomers were used as luting agents (Dyract, Fuji II LC and Vitremer), the results were comparable to those reported for the dentin bonding agents and the conventional method. SIGNIFICANCE: Light-cured resin-modified glass ionomer cements may be considered as an alternative to dentin bonding agents when the cavity margins of ceramic inlay restorations are within the dentin. However, further studies, e.g., wear resistance, must be performed.     

超音速等离子喷涂纳米防污陶瓷涂层研究

以NiCr合金为底层,含防污成分的纳米Al_2O_3-13%TiO_2为面层,采用超音速等离子喷涂方法制备纳米防污陶瓷涂层。研究了不同工艺对涂层截面形貌、孔隙率、显微硬度及结合强度的影响,探讨了涂层的防污性能,获得了较优的喷涂工艺参数:Ar流量3.6～3.8 m~3/h,H_2流量0.4 m~3/h,电流400～420A,电压150V,喷距100mm,送粉量30g/min。采用较优超音速等离子喷涂工艺制备的纳米防污陶瓷涂层孔隙率可达0.8%,HV_(0.3)≥987,结合强度≥35.15 MPa,并且抗海生物附着性能优良。     

Clinical comparison between a glass ionomer cement and a composite for direct bonding of orthodontic brackets

The clinical performance of a glass ionomer cement for direct bonding of orthodontic brackets was compared with a composite resin routinely used in this procedure. Brackets were bonded, using both materials, in alternate quadrants of 16 patients of the Orthodontic Clinic of the State University of Rio de Janeiro. A total of 225 teeth, 112 in the glass ionomer cement group and 113 in the composite group, were tested. Bond failure frequencies were recorded for 12 months, and chi-square statistical test was carried out comparing the failure rates of the materials. The composite showed a statistically significant lower failure rate (7.96%) than the glass ionomer cement (50.89%), regardless of the dental arch tested. Although the glass ionomer cement presents important properties not observed in the composite, it is necessary to increase its cohesive strength to permit its clinical use for direct bonding of orthodontic brackets.     

A 12-month clinical evaluation of a light-activated glass polyalkenoate (ionomer) cement for the direct bonding of orthodontic brackets

Glass polyalkenoate cements have the unique properties of physicochemically bonding to enamel and base metals and to leach fluoride over prolonged periods. These cements have been modified to provide a dual setting with both light activation and chemical cure to produce a more rapid set. This article reports a 12-month clinical trial of a light-activated glass polyalkenoate cement for the direct bonding of orthodontic brackets, compared with a standard composite bonding adhesive. There was no significant difference in failure rates of direct bonded orthodontic brackets cemented with Fuji II LC light-activated glass polyalkenoate cement (GC Industrial Co., Tokyo, Japan) (3.3%) compared with System I+ composite bonding resin (Ormco Corp., Glendora, Calif.) (1.6%).     

纳米氧化锆热障涂层完整性研究

分别采用超音速火焰喷涂技术(HVOF)与大气等离子喷涂技术(APS)喷涂NiCrAlY粘结底层, APS喷涂纳米氧化锆的方法获得了两种热障涂层(涂层A与B),并评估了热震试验前后涂层的完整性。试验结果表明:二者热震前,完整性基本相当,涂层结合强度为(55±5)MPa;但是经过热震试验后,涂层A具有更好的完整性。     

Tensile Properties of Surface-Treated Glass Fiber Reinforced PTFE Composite with Rare Earth Elements

The optimum amount of rare earth elements (RE) for treating glass fiber surface and its effect on the tensile properties of glass fiber reinforced polytetrafluoroethylene (GF/PTFE) composites were investigated. The tensile properties of GF/PTFE composites with different surface treatment conditions were measured. The fracture surface morphologies were observed and analyzed by SEM. The results indicate that rare earth elements can effectively promote the interfacial adhesion between the glass fiber and PTFE, owing to the effects of rare earth elements on the compatibility. The tensile properties of GF/PTFE composites can be improved considerably when the content of RE in surface modifier is 0.2%-0.4%,and the optimum performance of GF/PTFE composites is obtained at 0.3 % RE content.