Dissimilar Materials Structures

The effect of water in the service environment on bonded structures must be studied and evaluated in order to predict the long-term durability potential of any product that sees water exposure in its service environment. Water may invade the interfacial area along the interface or through the bulk of the adhesive with the distinct possibility that both pathways may be utilized simultaneously. The deleterious effect of water invasion of the bondline can be significantly accelerated if stress is being imposed simultaneously on the structure. Both factors must be evaluated at the same time when they can occur in the service environment. 

McGuire, American Adhesive Index, Padric Publishing, Mountainside, New Jersey (1962). 

Adhesive Materials, revised by C. V. Cagle, Foster Publishing, Long Beach, Calif. (1971). 

Schneberger (ed.). Adhesives in Manufacturing, Marcel Dekker, New York and Basel (1983). 

Handbook of Adhesive Bonding, McGraw-Hill, New York (1973). 

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Notice that these principles do not explicitly define the test parameters. However, the guidance documents developed by CDHR do provide accelerated aging protocols for specific devices within their jurisdiction based on the Q,q theory for chemical reactions. So, the theory postulated by Von t Hof using the Qio value (which states that a rise in temperature of 10°C will double the rate of chemical reaction) is the most convenient method of estimating the approximate ambient storage time equivalent at a selected accelerated aging temperature, despite flie Imown limitations and concerns for use on complex and dissimilar material structures. 

Piping should not be directly attached to dissimilar metal structures via conductive materials. 

Abstract—When K. L. Mittal asked me to provide a historical account of the applications of silane coupling agents in adhesion. I decided to write in the form of a personal account of my last 45 years in this line of study. No attempt is made to make the history comprehensive, or to recognize the host of other researchers who have contributed to our understanding of adhesion across an interface of dissimilar materials. It has been an immensely interesting area of study with many practical applications in composites and bonded structures. 

Dissimilar materials that constitute a corrosion couple Heat-sensitive materials Laminated structures... 

Interworked structures have been produced by various tools and techniques. What appear to be identical structures may have been executed by different tools and techniques. Moreover, identical fabric structures may present entirely different appearances and handles because of (a) the use of dissimilar materials, (b) the use of different tension during the manufacturing process, or (c) postfabrication treatment such as finishing, dyeing, and laundering. 

The impetus and the ultimate goal in chemical processing of ceramic materials is to control physical and chemical variability by the assemblage of uniquely homogeneous structures, nanosized second phases, controlled surface compositional gradients, and unique combinations of dissimilar materials to achieve desired properties. Significant improvements in environmental stability and performance should result from such nanoscale or molecular design of materials. 

Galwey et al. [13] supplemented kinetic measurements for the three salts with electron microscopic examination of partially and fully decomposed material. The significant differences in kinetic behaviour were attributed to the dissimilar lattice structures, variations in sizes and shapes of crystallites and disintegration of the reactant particles. The volatile and unstable copper(I) formate dimer [14] is... 

Corrosion can take place uniformly over a rubbed surface or selectively at surface inclusions, grain boundaries and between dissimilar materials, etc. For the former case, a problem results only if corrosion is excessive. Limited corrosion is necessary for anti-wear and extreme pressure protection. Selective corrosion can weaken surface structures and initiate fatigue. Moreover, abrasion is implicated in the promotion of corrosive wear since abrasive particles remove soft protective, corrosively formed, reaction films. 

Kellogg Chlorine Process. The Kellogg process uses 1% nitrosylsulfuric acid [7782-78-7] catalyst and a dissimilar material containing a day desiccant having a reversible water content of 0.5 wt% and a crystalline structure stable to at least 760°C (72,73). Montmorillonite [1318-93-0] is the desired clay desiccant. It absorbs water as it forms, shifting the equilibrium of equation 28 to the right. The basic reaction is carried out on a fluidized bed in which the solids run countercurrent to the gaseous reactants at a temperature of 400—500°C and pressures of 300—1200 kPa (3—12 atm). Nitrosylsulfuric acid catalyst is fed into the top of the stripper column where it reacts with HQ to form nitrosyl chloride which then reacts with 02 in the oxidizer to produce Clg. 

The step change in pore structure can be fabricated in discrete steps. It also allows the use of dissimilar materials for the porous structure, as used in early Westinghouse SOFC cathode designs and discussed by Thorogood et al. for oxygen transport membranes [12]. 

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