Solid-state bonding between Al and Cu by vacuum hot pressing

Diffusion bonding between aluminum and copper was performed by vacuum hot pressing at temperatures between 623 and 923 K through two thermal processes： hot compression under the deformation rate of 0.2 mrrdmin for 10 rain at pre-set temperatures, and additional pressing at 0.2 mm/min for 20 rain during furnace cooling. After analyzing interface, the feasible diffusion bonding temperature was suggested as 823 K. The three major intermetallic layers generated during diffusion bonding process were identified as AIECu, AlCu＋AlaCu4 and Al4Cu9. Furthermore, local hardness values ofAlECU, AlCu＋AlaCu4 and Al4Cu9 layers average at （4.97±0.05）, （6.33±0.00） and （6.06±0.18） GPa, respectively.

Diffusion Bonding of Al6061 and Cu by Hot Isostatic Pressing

Diffusion bonding between Al and Cu was successfully performed by hot isostatic pressing(HIP). To improve the strength of diffusion bonding joint, pure nickel foils with different thickness were used as intermediate layer. Microstructure of the interface between Al and Cu was investigated by X-ray diffraction(XRD) technique, secondary electron microscopy(SEM), and nano-indentation tests. When the temperature was 500 ℃ and held for 3 h with a processing pressure of 50 MPa, Al and Cu could be bonded with its interface formed by several diffusion layers. With the addition of Ni interlayer, the diffusion of aluminum atoms was effectively hindered, and the interface became smoother. The tensile strength of bonded joints increases with increasing the thickness of Ni interlayer, which contributes to a reduction in the thickness of intermetallic compounds(IMCs) and well bonding quality of Al-Cu joints.

Interfacial bonding strength of Al-Pb bearing alloy strips and hot dip aluminized steel sheets by hot rolling

Al Pb alloy strips and hot dip aluminized steel sheets were successfully bonded together by hot rolling, and the interfacial bonding strengths after rolling was evaluated by a new method. The bonding modes were studied by optical and scanning electron microscope and energy dispersive X ray analysis, and the effects of the thickness of the intermetallic layers and the Si content in hot dip aluminized layers on the interfacial bonding strength were also investigated respectively. It is found that the hot dipped steel and Al Pb alloy are bonded through blank interface bonding and block interface bonding, and the total bonding strength mainly depends on that of blank interfaces and the fraction of blank interfaces. There is a linear relationship between the total bonding strength F and the fraction of blank interfaces K b. The bonding strength varies with the Si content in the hot dipped aluminized layers on the surface of steel sheets, the fraction of blank interfaces and the rotation of the intermetallic blocks. [

Diffusion bonding of Ti−6Al−4V titanium alloy powder and solid by hot isostatic pressing

The Ti−6Al−4V(TC4)alloy powder and forged solid were diffusion bonded by hot isostatic pressing(HIP)to fabricate a powder−solid part.The microstructure of the powder−solid part was observed by scanning electron microscope(SEM).The microhardness and tensile tests were conducted to investigate the mechanical properties.The results showed that the powder compact was near-fully dense,and the powder/solid interface was tight and complete.The microhardness of the interface was higher than that of the powder compact and solid.The fractures of all powder−solid tensile specimens were on the solid side rather than at the interface,which indicated that a good interfacial strength was obtained.The tensile strength and elongation of the powder compact were higher than those of the solid.It is concluded that the HIP process can successfully fabricate high-quality Ti−6Al−4V powder−solid parts,which provides a novel near net shape technology for titanium alloys.

Effect of Reduction on Bonding Interface of Hot-rolled Wear-resistant Steel BTW1/Q345R Cladding Plate

Wear-resistant cladding plates consisting of a substrate（Q345 R） and a clad layer（BTW1） were bonded through hot rolling at the temperature of 1 200 ℃ and a rolling speed of 0.5 m/s. The microhardness of the cladding plate was also tested after being heat treated. The microstructure evolution on the interface of BTW1/Q345 R sheets under various reduction rates was investigated with a scanning electron microscope（SEM） and EBSD. It is found that the micro-cracks and oxide films on the interface disappear when the reduction is 80%, whereas the maximum uniform diffusion distance reaches 10 μm. As a result, a wide range of metallurgical bonding layers forms, which indicates an improved combination between the BTW1 and the Q345 R. Additionally, it is discovered that the unbroken oxide films on the interface are composed of Mn, Si or Cr at the reductions of 50% and 65%. The SEM fractography of tensile specimen demonstrates that the BTW1 has significant dimple characteristics and possesses lower-sized dimples with the increment in reduction, suggesting that the toughness and bonding strength of the cladding plates would be improved by the increase of reduction. The results reveal that a high rolling reduction causes the interfacial oxide film broken and further forms a higher-sized composite metallurgical bonding interface. The peak microhardness is achieved near the interface.

Hot embossing of micro energy director for micro polymer fusion ultrasonic bonding

In order to use micro ultrasonic bonding technique to package polymer microfluidic chips, an auxiliary microstructure named micro energy director is designed and fabricated. The hot embossing process for PMMA （ polymethyl methacrylate） substrates with both concave micro channel and convex micro energy director for ultrasonic bonding is studied. The embossing processes with different embossing temperatures are simulated using Finite Element Method （FEM）. The optimized parameters are： the embossing temperature of 135 ℃ , holding time of 200 s, and the embossing pressure of 1.65 MPa. The experimental results show that the replication error between experiments and simulations is less than 2% and the replication accuracy of the microstrueture is more than 96%. The study offers a method for quick optimizing parameters for hot embossing both concave and convex microstructures.

Interfacial structure and mechanical properties of hot-roll bonded joints between titanium alloy and stainless steel using niobium interlayer

The hot-roll bonding was carried out in vacuum between titanium alloy and stainless steel using niobium interlayer. The interfacial structure and mechanical properties were analyzed. The results show that the plasticity of bonded joint is improved significantly. When the bonding temperature is 800 °C or 900 °C, there is not intermetallic layer at the interface between stainless steel and niobium. When the bonding temperature is 1000 °C or 1050 °C, Fe-Nb intermetallic layer forms at the interface. When the bonding temperature is 1050 °C, cracking occurs between stainless steel and intermetallic layer. The maximum strength of -417.5 MPa is obtained at the bonding temperature of 900 °C, the reduction of 25% and the rolling speed of 38 mm/s, and the tensile specimen fractures in the niobium interlayer with plastic fracture characteristics. When the hot-roll bonded transition joints were TIG welded with titanium alloy and stainless steel respectively, the tensile strength of the transition joints after TIG welding is -410.3 MPa, and the specimen fractures in the niobium interlayer.

Effect of intermetallic compounds on heat resistance of hot roll bonded titanium alloy-stainless steel transition joint

The effect of intermetallic compounds on the heat resistance of transition joint was investigated. The experiment of post-weld heat treatment for the hot roll bonded titanium alloy-stainless steel joint using nickels interlayer was carried out, and the interface microstructure evolution due to heat treatment was presented. There was not found significant interdiffusion at stainless steel/nickel interface, when the specimens were heat treated in the temperature range of 600-800 °C for 10 and 30 min, while micro-cracks occurred at the stainless steel/nickel interface heat treated at 700 °C for 30 min. The thickness of intermetallic layers at nickel/titanium alloy interface increased at 600 °C, and micro-cracks occurred at 700 and 800 °C. The micro-cracks occurred between intermetallic layers or between intermetallic layer and nickel interlayer as well. The tensile strength of the transition joint decreased with the increase of heat treatment temperature or holding time.

Microstructure and mechanical properties of CuAgZn/GH909 diffusion bonded joint fabricated by hot isostatic pressing

The hot isostatic pressing-diffusion bonding(HIP-DB)was proposed to achieve the joining of CuAgZn and GH909 directly without an interlayer.The microstructure of joint was characterized by scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and X-ray diffraction(XRD).The microhardness and shear strength were tested to investigate the mechanical properties of joint.The results showed that the interface was complete,and the joint was compact,uniform and free of unbonded defects.The maximum microhardness of joint was HV 443,higher than that of two base alloys,and the average shear strength of joint reached 172 MPa.It is concluded that a good metallurgical bonding between CuAgZn and GH909 can be obtained by HIP-DB with the process parameters of 700℃,150 MPa and 3 h.

Effect of hot-humid exposure on static strength of adhesive-bonded aluminum alloys

The effect of hot-humid exposure(i.e., 40 C and 98% R.H.) on the quasi-static strength of the adhesive-bonded aluminum alloys was studied. Test results show that the hot-humid exposure leads to the significant decrease in the joint strength and the change of the failure mode from a mixed cohesive and adhesive failure with cohesive failure being dominant to adhesive failure being dominant. Careful analyses of the results reveal that the physical bond is likely responsible for the bond adhesion between L adhesive and aluminum substrates. The reduction in joint strength and the change of the failure mode resulted from the degradation in bond adhesion, which was primarily attributed to the corrosion of aluminum substrate. In addition, the elevated temperature exposure significantly accelerated the corrosion reaction of aluminum, which accelerated the degradation in joint strength.

Improvement of material properties and cladded flat product productivity with roll-bonding technology

Taking advantage of the progress of roll-bonding technology, the integrity of the material technology, and the development of the production and examination facilities of all the main carbon steels, stainless steels and specialty alloys in Baosteel, the cladded flat new products, which combined both properties of base material and clad material ,have been developed and produced in large quantities. The product categories includes heavy plates with high alloy content and homogeneous distribution in thickness and carbon steel plates cladded with all kinds of stainless steels ,nickel alloys ,and titanium alloys. The double-sided and single-sided cladding hot roiled strips and cold rolled sheets were also commercially produced. Due to the combined properties of both the cladding material and backing material, all products show obvious improvement in properties when compared with solid material. The comparability with the existing production process and equipment laid a very solid foundation for high productivity.

Study on process of roll bonding stainless and carbon steel under non-vacuum condition

The non-vacuum roll bonding method of nickel plating on the base materials is put forward in accordance with the primary problems existed in the roll bonding of stainless/carbon steel. After nickel plating test on the base materials, the microstructure of nickel cladding is observed by scanning electron microscopy （SEM） at high, and room temperature, and the results show that the nickel cladding on base material can be protected from oxidation in the high temperature. Non-vacuum roll bonding tests of nickel plating on base materials are done by the roll bonding equipment, and the roll bonding plates of stainless/carbon steel are obtained. The microstructure and the elements distribution of non-vacuum roll bonding interface are analyzed by optical microscope （OM） and SEM. The results reflect that the nickel plating layer and the base materials bond well.

折叠式手机玻璃的现状及发展

从直板机到折叠式机,随着手机的更新换代,推动了手机玻璃的发展。为适应折叠式手机要求,手机玻璃盖板必须具有柔性、韧性,可以弯曲折叠20~25万次,相当每天500次而不破裂,为此可选用叠层复合材料。叠层复合材料是由UTG超薄玻璃和CPI聚酰亚胺类型高分子材料保护膜通过热熔胶或热压贴合工艺形成的增强材料,利用UTG的刚性和CPI的塑性组合成韧性的叠层复合材料,从而提高折叠式手机玻璃盖板的抗冲击能力,将是今后手机玻璃的发展方向。

冲击加载下PBX界面对热点形成和安全性影响

高聚物粘结炸药(Polymer-Bonded Explosive,PBX)界面结构对其热点形成和冲击安全性有显著影响。为研究冲击条件下PBX点火响应过程,通过图像数字化建模和矢量化技术,建立反映PBX真实细观结构特征的有限元模型。考虑材料内部摩擦生热、晶体变形温升以及晶体放热反应过程,对PBX冲击载荷下热点形成进行数值仿真,并引入热点密度作为依据来判断材料是否点火,进一步研究晶体表面粗糙度和晶体包覆缺陷对材料点火感度与安全性的影响。试验结果表明:在冲击加载过程中,PBX内部热量前期主要来源于摩擦生热和晶体变形温升;当温度逐渐升高后,热量主要来源于晶体放热反应;材料发生点火的临界热点密度为0.68 mm-2,降低晶体表面粗糙度并提高晶体表面包覆质量,有助于抑制热点的形成,使材料降感,进而提升PBX安全性;研究结果可用于高能炸药的点火感度及安全性评估,并指导其生产加工与制备工艺。

HB400/HG70双金属工程机械钢热轧结合行为模拟研究

目的研究HB400/HG70双金属热轧过程中轧制温度、压下率和轧辊转速对应力、应变及温度分布的影响规律。方法利用ABAQUS有限元数值模拟软件,建立了HB400耐磨钢/HG70焊接钢双金属热轧有限元模型。结果当压下率从50%增加至60%时,HB400与HG70两侧等效应变差值增大,已结合的部位由于变形量加大和应力集中导致结合失效。当压下率为50%时,结合区域等效应变为0.77~0.87,两侧的平均等效应变差值为0.0047且最大值为0.01。轧制速度过快导致双金属未完全结合就离开了轧制区域,降低轧制速度可以使垂直轧制方向的应力分布更均匀,当轧制速度为0.6 rad/s时,HB400与HG70两侧等效应变没有明显差别。温度升高可以提高HB400与HG70两侧的变形均匀性。随着压下率的增加,复合板与轧辊的传热效率增强。复合板的温度下降更加明显。结论HB400与HG70双金属复合板的轧制协调性较好,无明显翘曲。热轧后双金属外侧应力大于结合区域应力;提高轧制温度、压下率和降低轧辊转速,能使垂直轧制方向的应力分布更均匀。最佳的热轧条件为温度1200℃、压下率50%、轧制速度0.6rad/s。

胶合板用高温花生粕和低温花生粕蛋白基胶黏剂的制备与表征

[目的]以高温花生粕(HPM)和低温花生粕(CPM)为试验原料,通过变性交联提高胶黏剂的胶接性能和耐水性,为花生粕蛋白基胶黏剂的进一步实际应用提供参考。[方法]采用尿素(U)变性和聚酰胺多胺环氧氯丙烷(PAE)树脂交联两步法制备HPM和CPM蛋白基胶黏剂,并比较其在胶合强度、黏度、官能团、热性能和微观形貌方面的差异。[结果]与未变性交联的HPM和CPM胶黏剂相比,变性交联后HPM和CPM胶黏剂制备的杨木胶合板干态胶合强度分别提高134.1%和111.4%,湿态胶合强度分别满足国家标准Ⅰ类和Ⅱ类胶合板要求;变性交联后HPM与CPM胶黏剂黏度分别提高101.5%和70.5%,热分解温度分别提高至316.44和307.57℃,且HPM制备的胶黏剂表面最紧密。[结论]变性交联后HPM胶黏剂的胶合强度、耐水性优于CPM胶黏剂,HPM比CPM更适宜作胶黏剂原料。

低温Au-Au键合工艺的研究

Au-Au热压键合工艺在微电子器件的制造与封装中有着广泛的应用。为了提高晶片键合质量,保证器件的稳定性和工作期限。在工艺试验过程中,首先利用超声波湿法清洗方法和氧等离子体处理方法对晶片表面进行处理,随后对晶片进行热压键合,最后利用超声波扫描显微镜来评估晶片的键合质量。实验结果表明,经过表面处理后晶片表面粗糙度降低,有效提高Au-Au热压键合的质量。空洞占键合面的比例由3.09%下降到了1.13%,另外键合界面拉伸强度也会更高,可以达到5.10 MPa。这种金属键合工艺有望在器件封装中获得广泛的应用。

动态再结晶对纯镍热压连接界面结合率的影响

为研究热压连接过程中显微组织演化与连接界面结合效果的关系,以纯镍试棒为载体进行单向热压模拟实验。通过采用不同温度和变形速率的组合,触发不同类型的不连续动态再结晶;对热压后的试棒进行室温拉伸测试和显微组织表征。结果表明:纯镍在动态再结晶过程中,当热压温度高至1100℃和热压变形速率低至0.001 s^(-1)的组合易于触发晶界弓出的再结晶方式,分体试棒连接界面的迁移效应显著,得到高的结合率;而当热压温度低至800℃和热压变形速率高至0.01 s^(-1)时易于产生亚晶合并的再结晶方式,其对界面迁移的影响相对较弱,分体试棒的界面结合率较低。亚晶合并耦合多相场法的界面迁移模型分析同样表明,亚晶合并形核仅能消除小角度晶界,而对大角度晶界(如连接界面)的消除效果较弱。

乙烯基三乙氧基硅烷(VTES)改性APAO-V基热熔胶及其性能研究

使用乙烯基三乙氧基硅烷(VTES)对聚α-烯烃(APAO)基热熔胶进行接枝改性,制备了高粘接强度、耐溶剂性、耐热性稳定的反应型聚α-烯烃-乙烯基三乙氧基硅烷(APAO-V)基热熔胶。探究了不同质量分数下VTES改性APAO后对所制备热熔胶体系各性能的影响,从而确定最佳配比。研究结果表明:(1)FT-IR曲线表明VTES发生水解进行自交联,VTES改性APAO成功;XRD衍射曲线表明VTES接枝APAO并未对其结晶形态产生影响。(2)当VTES的质量分数为8%时,VTES改性APAO基热熔胶的软化点、旋转黏度均达到最大值,分别为147.7℃、7025 mPa·s,APAO基热熔胶热稳定性能最好。(3)使用8%VTES改性APAO所制备的反应型APAO-V基热熔胶,改性后热熔胶的粘接强度在常温、高温(60℃)以及低温(-20℃)状态下均有提升,其中常温下粘接提升效果最好,剥离强度提升了15.0 N/cm。改性后热熔胶在浸水28 d后剥离强度仍能达到22.3 N/cm。(4)使用8%VTES改性APAO所制备的反应型APAO-V基热熔胶,比较热熔胶对4种不同塑料基材(PE、PVC、PP和ABS)的单搭接剪切强度,改性后APAO所制备的热熔胶的粘接性能均有很大程度的提升。

QAl10-4-4/TC6双金属连接界面组织与力学性能分析

铜合金/钛合金双金属材料能发挥各自的性能优势,兼具轻质、耐磨、高强等优异性能。本文通过真空热压扩散法连接QAl10-4-4铝青铜和TC6钛合金,并采用显微组织观察和剪切强度测试等方法,研究了直接连接和添加AgCuZnCd连接的QAl10-4-4/TC6双金属的界面组织和力学性能,探究了连接参数与中间层对QAl10-4-4/TC6双金属连接质量的影响规律,分析了双金属界面过渡层形成机理,建立了连接工艺-界面组织-力学性能的内在关联。结果表明:直接扩散连接的QAl10-4-4/TC6双金属连接质量较差,生成的金属间化合物导致界面上生长了贯穿长裂纹,剪切强度仅有21 MPa;添加AgCuZnCd连接QAl10-4-4/TC6双金属后界面金属间化合物减少,当连接温度为850℃时,界面剪切强度最大为178.19 MPa,温度超过850℃时,双金属界面强度迅速降低。