Investigation on reactive diffusion bonding of SiCp/6063 MMC by using mixed powders as interlayers

Mixed Al–Si, Al–Cu and Al–Si–SiC powders were used as interlayers to reactive diffusion bond SiCp/6063 MMC. The microstructure and the effects of bonding parameters on the shear strength of SiCp/6063 MMC joints were investigated. The results show that SiCp/6063 MMC joints bonded by using the interlayers of mixed Al–Si, Al–Cu powders have a dense joining layer of high quality. The mass transfer between the bonded materials and the interlayers during bonding leads to the hypoeutectic microstructure of the joining layers. Using mixed Al–Si–SiC powder as an interlayer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer. This is responsible for the low shear strength of the joints, even lower than those reactive diffusion bonded by using the interlayers of mixed Al–Si and Al–Cu powders. Ti added in the interlayer obviously improves the joint strength reactive diffusion bonded by using the mixed Al–Si–SiC powder.     

异种金属摩擦焊工艺温度场数值模拟研究

基于摩擦焊接过程中热-力学现象,建立摩擦焊接过程中热力耦合模型,对陶瓷/金属焊接过程中温度分布进行数值模拟。所提出的模型能够预测金属陶瓷摩擦焊接过程中随时间增量的温度分布情况;焊接界面区域产生的摩擦热消耗中间层铝,并在氧化铝和低碳钢之间建立焊接层。由于氧化铝和低碳钢具有不同的温度属性,在界面处会产生更多的热应力。数值模拟用来预测氧化铝/低碳钢接口处残余应力的变化情况,进而避免异种金属摩擦焊接过程中不完全联锁、接头强度差的现象。     

Microstructure and mechanical properties of diffusion bonded titanium/304 stainless steel joint with pure Ag interlayer

Abstract

In the present study, diffusion bonding of commercially pure titanium to 304 stainless steel (SS) using a pure Ag interlayer was carried out. It is found that the pure Ag interlayer can effectively block the interdiffusion and interaction between Ti and SS. The resultant joints were composed of Ti substrate, Ti–Ag solid solution, TiAg intermetallic phase, the remnant Ag interlayer and SS. Upon tensile loading, fracture took place through the remnant Ag interlayer, indicating that the TiAg intermetallic phase exhibits no detrimental effect on the strength of the joints. A maximum tensile strength of 421 MPa was achieved, which is notably improved compared with previous results. Furthermore, extensive dimples were observed on the fracture surfaces, clearly indicating that the joints were ductile in nature.     

300MW汽轮机夹层加热装置的运行研究

为了使汽轮机在启动过程中膨胀均匀,降低汽缸各项温差,缩短机组启动时间,大型汽轮机一般都设置了汽轮机夹层加热装置。针对东方汽轮机厂生产的300MW汽轮机汽缸夹层加热装置,根据加热系统工作原理和实际运行经验,总结出夹层加热装置的操作方法,并对系统应用的注意事项及容易发生的异常进行分析并加以解决。     

Interlayer expansion of dimethyl ditallowylammonium montmorillonite as a function of 2-chloroaniline adsorption

The expansion behaviour of an organically modified montmorillonite during the adsorption of increasing amounts of an organic pollutant: 2-chloroaniline (2-CA). The organophilic montmorillonite, a commercial product, was obtained exchanging the inorganic cation with dimethyl ditallowylammonium ions (DMDTA). 2-CA was added to the organoclay, starting from 193.9 ppm up to 23,531.7 ppm going through twenty-two steps of growing quantities of 2-CA. For each of these twenty-two steps – corresponding to a range of adsorbed 2-CA (C_s) between 0.029 mol/kg (grams of 2-CA per kg of organoclay) and 2.763 mol/kg – the basal spacings were determined.The adsorption isotherm was performed according to ASTM D 4646-87 Standard and, by comparing the experimental C_s data with the corresponding d₀₀₁ values, the basal expansion of the polluted organoclay is characterized by a steep rise for the first steps of adsorption of 2-CA (concentration in water at equilibrium C_w < 0.00373 mol/L), then the d₀₀₁ remains almost constant up to the higher amounts of pollutant adsorbed.The 001 reflections are sharper, their intensity higher, and up to four orders of 00l reflections are observed as the uptake of 2-CA increased. Since in aqueous solution the staking of organoclay platelets is poorly ordered, the observed behaviour may be partially explained by the 2-CA sorbed on the external surface of the clay mineral particles, which brings the silicate layers together.Finally, a tentative interpretation of the adsorption phenomena was carried out by fitting the experimental data according to the most common theoretical models: Freundlich, Langmuir, Dual Mode and Dual Langmuir Model.     

Transient thermal loading induced optical effects in single-coated optical fibers with interlayer thermal resistance

The transient microbending loss and refractive index changes in a single-coated optical fiber subjected to thermal loading with stress-dependent interlayer thermal resistance are investigated. The effects of interlayer thermal resistance on the transient microbending loss and refractive index changes of the optical fiber are analyzed and discussed. Results show that the interlayer thermal resistance will increase the transient thermal loading induced lateral pressure in the single-coated optical fiber and, thus, the microbending loss. To the contrary, the interlayer thermal resistance will decrease the transient thermal loading induced refractive index changes.     

分层采油工艺管柱的研究与应用

为有效降低钻采、开发成本,华庆油田研究应用分层采油技术,在实践中发现,部分井因为封隔器坐封载荷过大造成管柱弯曲,分采泵无法正常抽汲,针对这一问题,研究设计了新型分采工艺管柱,现场试验表明,该分采技术不但能有效控制坐封载荷,还能有效解决层间干扰,提高单井产量。     

New procedure for measuring adherence between a geosynthetic material and a bituminous mixture

The aim of this investigation was to analyze the adherence between two layers of bituminous mixture when a geosynthetic material is placed between them. A new monotonic test procedure was developed that enables the evaluation of the influence of the binder type and content, and the typology of the geosynthetic material used. The validity of the procedure was demonstrated using dynamic tests. The results confirmed that highest adherence between layers is obtained through geogrids, with optimal residual binder content of 0.30 kg/m². In contrast, the tests with geotextiles were found to be less sensitive to binder content, with lower shear resistance for higher contents of binder.     

钻井液组分对泥饼抗剪强度的影响

钻井液组分直接影响井内泥饼的成分和性质,并最终影响隔层界面处泥饼的力学性能。为研究钻井液不同组分对泥饼抗剪强度的影响机理,综合运用土的重塑和直剪实验,分别测量膨润土重塑土、膨润土-铁矿粉重塑土、膨润土-石英砂粉重塑土的抗剪强度指标,研究钻井液泥饼中的黏土矿物、加重材料和钻屑3类固相物质对界面泥饼的抗剪强度影响。结果表明,在一定含水率和压实程度下,随着泥饼中铁矿粉含量的增大,泥饼的内摩擦角和黏聚力均线性减小;当泥饼中石英砂粉质量分数低于10%时,泥饼的内摩擦角和黏聚力均线性减小;而当泥饼中石英砂粉质量分数高于10%时,泥饼的内摩擦角、黏聚力变化不大;一定范围内,泥饼中膨润土含量增加有利于提高泥饼黏聚力。     

中间层厚度对TiAl金属间化合物三体摩擦焊接性的影响

利用Inconel718中间层实现了TiAl金属间化合物与42CrMo钢的三体摩擦焊接，焊接接头拉伸强度达到360MPa左右。采用数值逼近方法得到了中间层厚度与拉伸强度之间的数学模型，并对接头组织性能进行了理论分析。