Joint between two metals

The largest amount of tin used in the United States goes to the production of solder (typically pronounced SAH der in the United States). Solder is an alloy, usually made of tin and lead, with a low melting point. It is used to join two metals to each other. For example, metal wires are attached to electtical devices by means of solder. Solder is also used by plumbers to seal the joint between two metal pipes. 

Solder is often applied by means of a soldering iron. A soldering iron consists of a steel bar through which an electric current runs. The electric current heats the bar as it passes through it. When a small piece of solder is placed on the tip of the soldering iron, it melts. The solder is then applied to the joint between two metals. When it cools, the bond is strong. In 2007, more than 50 percent of tin consumption was for solder. 

The Peltier effect is well known. It is encountered at the joint between two metals. It is generally spoken of at the same time as the Thomson effect, because these two effects both cross-link between the thermal gradient and intensity of the current. 

Where it is desired to construct a joint between two metal parts in tension, allowance must be made for the difference in strength of the particular metal section and the adhesive selected. If the metal is ten times stronger than the adhesive, it is apparent that the area of the joint surface must be ten times greater than the cross sectional area of... 

A flat sheet or shaped section of rubber compound or rubber textile composite fitted between two metal faces to make a fluid-tight joint. 

The ducts must be insulated following the characteristics of the air inside T° < 18°C should be insulated with armaflex thickness = 25 mm. The insulation must be glued on the ducts. The joints between two strips of insulation must be airtight (gluing of an insulation strip on the joints) to prevent condensation on the pipe. Return ducts, blow ducts (T > 18°C) should be insulated with rockwool or glasswool (thickness = 25 mm recovered by a metallized vapor barrier). 

It was shown in Section 11.C.8.C how numerical simulations can be used to predict whether failure is more likely to occur via a cohesive or an adhesive mechanism in a joint consisting of an epoxy thermoset glue between two metal plates. 

Rubber-to-metal adhesion was determined by tensile testing a rubber specimen cured between two metal coupons as illustrated in Figure 8.6. The tensile test was run at 2.5 cm/minute crosshead speed and the force in kg to break the lap joint in shear was measured. The rubber specimen, approximately 0.08 cm thick, was cured at 160 -166 °C for 30 minutes between two 2.5 x 7.6 x 0.08 cm metal coupons overlapped 2.5 cm in a plaque mould under 207 MPa pressure (Figure 8.6). The metal coupons were methanol washed and dried before curing. 

Finally, reference should be made to the extensive and recent durability evaluations of rubber-to-steel bonded joints in seawater. These kinds of bonds have been of especial interest to the fabricators of the deep ocean oil rigs. Stevenson ) has shown that the rate of adhesive bond failure between two metals of different electrochemical potential have special qualities that need to be understood by the designer. First, however, he demonstrated that mechanical strain in the elastomer layer did not seem to have any effect on bond durability. Furthermore, if the two adherends were electrochemically inert then the bonds were completely stable after periods as long as three years in saltwater. There was, however, an expected result when one adherend was more noble. While that adherend would be less corroded because of the electrochemical protection by the more anodic adherend, there was also a distinct increase in the rate of adhesive bond failure at that interface. 

However, the forces that are involved in making a bond, the interaction between the liquid with the substrate then transformation from liquid to sohd are very different from those occurring when breaking a bond. When an adhesive joint is put under stress, it is not only the adhesive that distorts, the substrate does too. For example, a lap joint between two moderately flexible materials such as metals... 

This test is applicable to all outdoor metal-enclosed switchgear and controlgear assemblies, as in lEC 60298, lEC 60694 and ANSI C-37/20C. The enclosure to be tested should be complete in all respects including its mounts, bushings (for HT switchgear assemblies, 1 kV and above) and wiring. One or more vertical units can be tested simultaneously as may be convenient, but not more than 3 m panel width can be tested at a time. For a multiple unit switchboard, however, at least two vertical units should be tested together to check the joints between the units. 

The electrochemical examination of fusion joints between nine pairs of dissimilar metal couples in seawater showed that in most cases the HAZ was anodic to the weld metals" . Prasad Rao and Prasanna Kumarundertook electrochemical studies of austenitic stainless steel claddings to find that heat input and 5Fe content significantly affected the anodic polarisation behaviour under active corrosion conditions whilst Herbsleb and Stoffelo found that two-phased weld claddings of the 24Cr-13Ni type were susceptible to inter-granular attack (IGA) as a result of sensitisation after heat treatment at 600°C /pa was unaffected by heat input. 

An important result of the concepts discussed in this section and the preceding one is that precipitation and complexation reactions exert joint control over metal ion solubility and transport. Whereas precipitation can limit the dissolved concentration of a specific species (Me ), complexation reactions can allow the total dissolved concentration of that metal to be much higher. The balance between these two competing processes, taking into account kinetic and equilibrium effects, often determines how much metal is transported in solution between two sites. 

Various commercial adhesives have been used to provide bond strength with nylon on the order of 250 to 1000 psi. Priming of nylon adherends with a composition based on resorcinol formaldehyde, isocyanate modified rubber, and cationic surfactants has been reported to provide improved joint strength. Some epoxy, resorcinol formaldehyde, phenol-resorcinol, and rubber-based adhesives have been found to produce satisfactory joints between nylon and metal, wood, glass, and leather. Exposure of nylon 6 to oxygen and helium plasmas for 30 s to 1 min improved the adhesion of two-part epoxy adhesives.66... 

Dielectric test methods are used to measure the cure of epoxy adhesives between two conducting electrodes. This method is especially appropriate for metal-to-metal joints because the substrates themselves can be used as the electrode. The adhesive is treated as a capacitor during the test. Its response (dielectric constant, dissipation factor, etc.) over a range of electrical frequencies is measured as a function of curing time. 

Electrical methods. The electrical methods of measuring temperature are based on two facts, firstly, that the resistance of a conductor varies with the temperature, and secondly, that the electromotive force which is produced at a point of contact between two different metals or alloys is hkewise a function of the temperature. If, therefore, we close a circuit consisting of two wires of different metals, so that there are two joints in the circuit where two metals meet, a current will flow in general so long as these joints are not at the same temperature. If the temperature of the one joint is known, a measurement of the electromotive force enables us to determine the temperature of the other. On account of the great sensibility of electrical measurements, it is possible to measure very small differences of temperature by either of these methods. They have the further advantage over the first and second methods, that we are enabled by their means to measure very high and very low temperatures in a most convenient manner. The small bulk occupied by a thermocouple is often important from an experimental point of view, and for this reason thermocouples are preferable in some cases to all other forms of thermometer. 

Parallel to the development of the chemistry of dinuclear transition metal complexes with metal-metal bonds, studies related to bimetallic complexes, hetero- and homonuclear, without metal-metal bonds are appearing in the literature at ever increasing frequency (10-13). In these complexes, two or more metals are separated by a common ligand which acts as a bridge between them. Two metal centers acting in a joint fashion could enhance the activation of an organic substrate considerably and in... 

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