Dissimilar materials, joining

Regardless of which reasoning is preferred, obviously the best answer is to have the tank fabricated with the bottom already sloped, and to avoid the use of two totally dissimilar materials joined together. 

Refractory Metal Irradiation Embrittlement, Creep, Dissimilar Material Joining... 

Turbine Casing (scroll) In-792 Upto 1150 K Creep Capability, Dissimilar Materials Joining (to piping)... 

Bonding permits the joining of dissimilar materials, and since adhesives are generally dielectric materials, their use minimizes the possibility of electrolytic corrosion when different metals are joined. 

There are also two well-known thermoelectric effects resulting from the joining of dissimilar materials (forming a junction) the Seebech effect, on which thermocouples are based, and the Peltier effect, used for thermopiles. The Seebech effect results when the two junctions of the dissimilar materials are held at different temperatures. The Seebech coefficient, e, is defined as the open-circuit voltage generated per unit temperature differential of the two junctions ... 

A variety of techniques is available for joining plastics to themselves or to other materials—mechanical fastening, welding, and bonding with adhesives—and all are used extensively. Each method has both advantages and drawbacks for plastics, bonding might be said to be preferable when they are to be joined with dissimilar materials. 

The operation principle of a thermocouple is described by the Seebeck effect When two dissimilar materials are joined together at two junctions and these junctions are maintained at different temperatures, an electromotive force (EMF) exists across the two junctions. 

The Ba0-Ca0-Al203-Si02 (BCAS) glass ceramic seal is often used for joining dissimilar materials, i.e. ceramic cells, metallic manifolds and metallic interconnects [2]. The ceramic seal should possess a satisfactory matching of the thermal expansion coefficient with the cells and the chosen alloy and it should also exhibit a long-term stability under the operation conditions. 

THERMOELECTRICITY - In physics, electricity generated by the application of heat to the junction of two dissimilar materials. If two wires of different materials are joined at their ends and one end is maintained at a higher temperature than the other, a voltage difference will arise, and an electric current will exist between the hot and the cold junctions. 

In order to facilitate this shift toward lighter materials, designers have had to identify an appropriate method of joining new and dissimilar materials. The joining method must be fast and easy to achieve, and the resultant joints need to be strong and durable (at least on a par with the performance of welding and other traditional methods of joining steel components). This is where structural adhesives have helped to make a big difference. 

Dissimilar materials, including plastics, are readily joined by many adhesives, provided that proper surface treatments are used. Adhesives can be used to join metals, plastics, ceramics, cork, rubber, and combinations of materials. Adhesives can also be formulated to be conductive. The focus of this book is on adhesives for bonding plastics, thermosets, elastomers, and metals. 

The technique selected depends on whether the ceramic is to be joined to a similar or dissimilar material, and on the expected operational conditions at the joint. If the joint temperature is not expected to exceed 150°C or to only have very short-term excursions to 200°C, and the environment is not too chemically aggressive, organic adhesives offer an attractive joining solution. 

The primaiy problem in Joining dissimilar materials is the difference in thermal expansion. When the Joint is used at any temperature other than the cure temperature of the adhesive, the adhesive will be stressed owing to the relative movements of the adherends. These stresses may become high enough to cause the joint to fail without external loads. It is possible to calculate these stresses analytically together with the stresses from the mechanical loading. Procedures for single-lap and double-lap Joints are presented in 5.3.5. When the members to be Joined have dissimilar thermal expansion behaviour, ductile adhesives are preferred. 

According to Hart Smith the adherend stiffnesses should be balanced as much as the relative strengths of the adherends permit (i.e. product Et should be kept constant). This needs to be considered only when two dissimilar materials are joined together. 

A process of joining two similar plastic materials to themselves or to dissimilar materials by means of solvents. 

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