金属工件的表面处理及胶接工艺对胶接剪切强度的影响

采用环氧树脂-DDS固化体系作为胶接剂,探讨了各种金属表面处理方法、胶接时对胶接面施加的压力、胶层厚度等因素对胶接剪切强度的影响.结果表明,对不锈钢工件采用盐酸氧化法及草酸-硫酸氧化法进行表面处理,得到的胶接剪切强度最好;对铝合金工件采用硅酸磷酸钠法进行表面处理,得到的胶接剪切强度最高.胶接时对胶接面施加0.1～0.4Mpa的压力、胶层厚度在0.10～0.23 mm范围内时胶接效果最好.由于处理液对金属表面产生适度的化学腐蚀,改变了金属表面的物理化学性质,表现出更好的可浸润性和更强的表面吸附力,可以有效地提高胶接剪切强度.     

An experimental study on the dependence of the strength of adhesively bonded joints with thickness and mechanical properties of the adhesives

Adhesive bonding joints are widely applied in many engineering fields. Their overall strength is much dependent on the thickness of adhesive layers. Many previous experimental studies have found that the ultimate failure strength of the bonding structure increases with the decrease of the adhesive thickness. However, few of them consider the effect of adhesive intrinsic material parameters on the relation between the overall strength and adhesive thickness. In the present investigation, the effect of the adhesive thickness on the overall strength of the lightweight metallic adhesive bonding joints was experimentally studied, considering the effect of the adhesive toughness. The results show that the variations of overall strength resulting from the adhesive thicknesses have remarkable discrepancy due to the toughness of the adhesive, which is in agreement with the previous model prediction.     

鱼鳔及其鱼鳔胶粘剂(三)鱼鳔胶粘剂的力学性能

实验以三种不同的鱼鳔 ,在考查固胶物化性能的同时 ,探索了胶接工艺对胶接性能的影响 ,结合实际应用对基材试件、胶接试件等有关力学性能作了研究     

On the effect of pulsed laser ablation on shear strength and mode I fracture toughness of Al/epoxy adhesive joints

The present work describes an experimental study about the shear strength and the mode I fracture toughness of adhesive joints with substrates pre-treated by pulsed laser ablation. An ytterbium-doped pulsed fiber laser was employed to perform laser irradiation on AA6082-T4 alloy. Morphological and chemical modifications were evaluated by means of surface profilometry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Thick adherend shear tests were carried out in order to assess the shear strength while the mode I fracture toughness was determined using the double cantilever beam. For comparison, control samples were prepared using classical surface degreasing. The results indicated that laser ablation has a favorable effect on the mechanical behavior of epoxy bonded joints; however, while a + 20% increase was recorded for shear strength, a remarkable threefold enhancement of fracture toughness was observed with respect to control samples. XPS analyses of treated substrates and SEM observations of the fracture surfaces indicated that laser pre-treatment promoted chemical and morphological modifications able to sustain energy dissipation through mechanical interlocking. As a result cohesive failure within the adhesive bond-line was enabled under predominant peel loading.     

水性聚氨酯热熔胶的制备及性能

以甲苯二异氰酸酯、聚己二酸-1,4-丁二醇酯(PBA)、聚环氧丙烷醚三醇(PPO)为主要单体,2,2-二羟甲基丙酸(DMPA)为羧基单体,1,4-丁二醇为扩链剂合成了聚氨酯预聚体,并以三乙胺为中和剂,进一步制备了阴离子水性聚氨酯乳液。考察了交联单体PPO含量对乳液及胶膜性能的影响。结果表明,n(PBA)∶n(PPO)=9∶1时,乳液稳定性好,聚氨酯膜的拉伸强度为44.18 MPa,断裂伸长率为742.94%,其热分解温度为239℃,对皮革的黏接强度高于皮革的内聚强度,对不锈钢的黏接剪切强度为14.76 MPa。     

工艺条件对拉伸试件粘接强度分散性的影响

以铝和丁基橡胶的粘接拉伸试件为研究对象,结合粘接过程被粘面表面处理、涂胶、加压、固化等主要工序,讨论了粘接工艺方式和粘接过程控制对拉伸试件粘接强度分散性的影响。结果表明,在粘接过程中采用适当的表面处理方法、涂胶方式,确定适当的加压压力、涂胶厚度和固化条件,有利于减小粘接件拉伸强度数据的分散性并提高粘接强度。     

40℃固化高强度高剥离耐热环氧树脂胶粘剂

介绍了一种８０℃固化,耐热１３０℃结构胶粘剂,该胶具有良好的综合性能。     

固化工艺参数对胶粘剂180°剥离强度的影响

以自制胶粘剂为基础,研究了剥离强度测试用样条的制备工艺对180°剥离强度的影响。结果表明:样条制备时的温度、压力、时间、胶层厚度和被粘材料表面粗糙度等因素对剥离强度影响较大,并且有一定的规律性,说明对每种胶粘剂的剥离强度测试,除统一测试标准外,还需研究测试用样条的适宜制备工艺,以降低剥离强度的测试误差。     

工艺参数对低粘度建筑结构胶粘接强度的影响

对影响建筑结构胶粘接强度的各工艺参数进行了试验研究,确定了低粘度结构胶最佳固化工艺参数,并结合工程施工提出相应解决措施。     

固化温度对缓凝黏合剂固化时间和强度的影响

为研究固化温度对缓凝黏合剂固化时间和强度的影响,将缓凝黏合剂在固化温度分别为25、45、65、85 ℃的条件下养护。通过邵氏硬度试验研究了3种缓凝黏合剂在不同固化温度条件下的固化速率,测试了缓凝黏合剂在不同固化温度条件下的拉伸剪切强度、抗折强度和抗压强度。结果表明,固化温度越高,缓凝黏合剂固化时间越短,以25 ℃为基准,45 ℃条件下的固化时间缩短约50 %,45 ℃以上,温度每升高20 ℃,固化时间缩短约10 %;以25 ℃条件下的强度为基准,缓凝黏合剂在不同固化温度条件下拉伸剪切强度的变化率在6 %内,抗折强度的增加率在6 %~45 %,抗压强度的增加率在9 %~50 %。     

Multiple high-temperature resistant phases modified phosphate-based adhesive for engineering ceramic connection in extreme environment

The lower-strength defect of inorganic phosphate adhesive had been definitely improved by self-generating multiple high-temperature resistant phases. Compared to our previous product, the best bonding performance of this novel adhesive for mullite was increased by 270%, which was close to some popular preceramic polymer-based adhesives. The apparent shear strength at room temperature was up to 33.1?MPa after calcination at 900?°C, while the high-temperature strength researched 23.3?MPa at 900?°C and maintained above 17?MPa from 700° to 1200?°C. The reinforced effect of adhesive owed to the introduction of various Cu-based intermetallics, the premature generation of Al₄B₂O₁₈ at 900?°C, and the structure optimizing through the oxidization of Si and B₄C. Besides, the novel adhesive displayed good resistance to thermal-shock, especially for air-cooling test. After 15 thermal cycles in air, the residual strength of 1300?°C-calcined joints was still above 13?MPa (~40%).     

Reliability analysis of bonded joints with variations in adhesive thickness

Bonded joints are used in several industrial applications as a surrogate of more expensive repairs, but their reliability must be ascertained. Failure in a bonded joint mainly occurs in the adhesive due to stress concentrations that directly depend on the adhesive thickness. In practice, it is difficult to ensure a good accuracy of the final adhesive thickness, leading to uncertainty to its spatial variability. This uncertainty greatly influences the strength of the bonded joint. This work deals with one of the main key issues in bonded joints: the influence of the spatial variations in the adhesive thickness on the reliability of the joint and an excessive shear stress level caused by the adhesive thickness variations may lead to failure. This paper provides reliability analysis by considering the adhesive thickness as a stochastic field. The experimental thickness field is obtained so as to identify the stochastic parameters. These parameters are then introduced in a structural reliability model to evaluate the failure probability. Results show the influence of adhesive thickness uncertainty on bonded joint failure.     

服装面料用聚氨酯胶黏剂的研制

介绍了用扩链剂A、混合多元醇和异氰酸酯等材料合成了适合服装面料行业所需的聚氨酯胶黏剂。简单介绍了聚酯多元醇和聚氨酯的合成工艺。研究讨论了多元醇的类型、扩链剂的结构、异氰酸酯指数、溶剂等方面对聚氨酯胶黏剂性能的影响。最终确定的以混合多元醇、扩链剂A、异氰酸酯和混合溶剂等原料合成的聚氨酯胶黏剂其外观澄清透明、软化点在1 0 0～ 1 1 0℃、固含量 35 %时黏度在 1 0 0 0 0～ 2 0 0 0 0mPa·s之间、硬度为 70～ 80邵氏A ,且贮存稳定     

四种原料生物油-酚醛树脂胶粘剂特性研究

利用生物质快速热解液化产物制备燃料或化工产品已成为国内外的研究热点。将四种生物质原料(落叶松、杨木、棉秸秆和玉米秸秆)快速热解液化产物作为苯酚替代物,由此制备出不同种类的热解生物油-PF(酚醛树脂)胶粘剂,并探讨了胶粘剂胶接强度与热解生物油组成的关系。结果表明:落叶松热解生物油-PF胶粘剂的胶接强度最大(1.277 MPa),玉米秸秆热解生物油-PF胶粘剂的胶接强度最小(1.021 MPa);胶粘剂的胶接强度主要与热解生物油中酚类物质含量有关。     

稀释剂对有机玻璃粘接用UV固化胶黏剂的影响

活性稀释剂对uv固化反应过程有重要的影响。为了考察稀释剂对有机玻璃粘接用uV固化胶的影响,采用复配法重点考察了稀释剂的种类、含量配比、表面张力等对有机玻璃粘接用uV胶黏剂的粘接性能的影响。结果表明,采用单官能团稀释剂IBOA和双官能团稀释剂TPGDA进行复配,其混合比例控制在（1：1）,总量控制在胶黏剂的50％一55％对有机玻璃的粘接效果最佳。     

用X射线仪热分析仪研究影响磷酸氧化铜胶的粘接强度因素

用X射线粉末衍射仪和综合热分析仪对不同固化用具、不同固化温度的YW -Ⅰ磷酸氧化铜无机胶进行较系统分析、研究 ,找出了影响粘接强度的因素。     

水溶性底胶在PVDC涂敷薄膜生产中的应用

介绍了水溶性底胶的定义、性能,采用水溶性底胶生产PVDC涂敷薄膜时烘干和冷却步骤的注意事项,国内外水溶性底胶性能现状;比较了采用水溶性底胶或溶剂性底胶生产的PVDC涂敷薄膜的性能;展望了水溶性底胶在PVDC涂敷薄膜生产中的应用前景。