Adhesion oxides

Metal to ceramic (oxide) adhesion is very important to the microelectronics industry. An electron transfer model by Burlitch and co-workers [75] shows the importance of electron donating capability in enhancing adhesion. Their calculations are able to explain the enhancement in adhesion when a NiPt layer is added to a Pt-NiO interface. 

Reliable data in the literature for the stress versus strain properties of composite propints are exceedingly difficult to find. Since the binder chemical properties and curing additions are susceptible in many cases to hydrolytic degradation, the exact formulations under test should be specified. Additionally, the binder to oxidizer adhesion properties are dependent upon particle size distribution used in the pro-pint. This should be specified and in almost all literature sources unearthed, it remained unknown. As some of these data show, the manner of conducting the test and control of such... 

While a non-phosphated topcoat/adhesive interface provided an excellent, moisture resistant, occlusive seal even under the most severe cycle testing, phosphated ZM adherends did not prove to be as durable in comparison (Figure 11). The reason for this lies in the fact that phosphate coverage on Zincrometal is incomplete. Partially crystalline phosphates are non-uniformly interspersed on randomly exposed zinc dust spheres at the surface. Consequently, the moisture resistance normally provided at the adhesive/topcoat interface was reduced due to the incomplete sealing between the topcoat/ adhesive surfaces. This became apparent as most of the failures examined after aging in these environments were concentrated at the adhesive/phosphate/paint interface. Results obtained on these samples were similar to those obtained for phosphated CRS joints, indicating that the locus of failure occurred at phosphate crystal sites. Note, however, that the durability of these joints was still considered to be very good in comparison to other metallic oxide/ adhesive interfaces. 

I For the case of copper, a mixture of cuprous and cupric oxides is present on the copper surface which acts as a defect semiconductor. Therefore, electrons can readily be transported from copper to its oxide surface allowing oxidation to continue at the metal oxide/adhesive interface ls. This continued oxidation reaction which involves the base metal can interfere with adhesion between the oxide and the adhesive. Hence, the underlying metal atoms can effect the adhesion forces in some cases 171... 

Extensive interface research is crucially essential for developing long-life, cost-effective, multilayer, polycrystalline, thin-film stacks for SECS. Microchemical analysis and other interface measuring techniques must be employed to solve the interfacial stability problems in the stacks. Important topical areas in solar materials interface science include thin films grain, phase, and interfacial boundaries corrosion and oxidation adhesion chemisorption, catalysis, and surface processes abrasion and erosion photon-assisted surface reactions and photoelectrochemistry and interface characterization methods. 

The nature and characteristic of these oxide layers depend on the base metal and the conditions that were present during its formation. With steel, for example, the oxide adhesion to the base metal is very weak. In the case of aluminum, however, the oxide is extremely stable and clings tightly to the base metal. In fact, it adheres so well that it serves as a protective coating for the aluminum, which is one reason why aluminum is a corrosion-resistant metal. Certain metals possess surfaces that interact more effectively with one type of adhesive than with another. This is the reason why adhesive formulators need to know as much as possible about the surfaces being assembled. 

Equation (6.11) has been used to calculate the contribution of van der Waals interactions to the metal/oxide adhesion energy (McDonald and Eberhart 1965,... 

Nakasaki et al.146 addressed the tungsten-oxide adhesion problem using reactively sputtered TiN as adhesion layer. A minimum thickness of 100 A TiN was needed for adhesion. 

Brown. S. Engineered iron oxide-adhesion mutants of the Escherichia coli phage a, receptor. Proc. Natl. Acad. Sci. U. S. A. 1992. 89, 8651 8655. 

Demand of additional materials for oxide adhesion respectively oxide removal. 

Isopropyl titanium triisostearate Methacrylic acid 2-Methylacrylic acid 2-(2-oxo-imidazolidin-1-yl) ethyl ester Methyltrimethoxysilane Oleic aminoethylimidazoline PEG-3 dimethacrylate PEG-6 trimethylolpropane Pentaerythrityl-tris-(B-(N-aziridinyl) propionate Polyethylenimine Propylene/MA copolymer PVPA/A copolymer Rosin, polymerized Styrene/allyl alcohol copolymer Styrene/MA copolymer Tallowaminopropylamine Tetraisopropyl di (dioctylphosphito) titanate Triallylcyanurate Tricaprylyl methyl ammonium chloride Trimethylolpropane tris-(B-(N-aziridinyl) propionate) Tris [1-(2-methyl-aziridinyl) phosphine oxide] adhesion promoter, acrylic resins... 

Other possible interfacial degradative mechanisms include the build up of osmotic pressure at the oxide/adhesive interface(6) (akin to the phenomenon of paint blistering by osmotic gradients), disbonding by alkali produced by the cathodic reaction in metallic corrosion(107), and the imposition of stress leading to bond stress-corrosion cracking( 108-110). 

The failure mode of samples exposed for long times is gradual undercutting of the adhesive bond at the metal oxide/primer or metal oxide/adhesive interface. This is shown schematically in Pig. 14. This undercutting continues until the remaining bonded surface is not enough to support the load. 

In general, the kinetic energy of the evaporated particles is substantially less than that of sputtered particles. This requires that the substrate be heated to about 300°C to promote the growth of the oxide adhesion interface. This may be accomplished by direct heating of the substrate mounting platform or by... 

Buchwalter, L. P., Adhesion of Polyimides to Metals and Metal Oxides, Adhesion Sci. Technol, 1(4) 341-347 (1987)... 

Another important aspect of testing the adhesive as part of an adhesive-joint system is that the joint presents a number of options for the location of the failure path. Failure may be cohesive in approximately the center of the adhesive layer. It may be cohesive but near the interface as is often seen in peel testing. It may be interfacial along the adhesive-substrate interface or it may run entirely within an interphase, for example, within a metal oxide/ adhesive interphase region. The failure path could run cohesively through the substrate, for example, the crack could run in the interlaminar region of a fiber-reinforced polymer composite substrate (Kinloch et al. 1992). Finally, some combination of the above could occur. Each of these options for the failure path may lead to a different fi-acture resistance being measured and thus adhesive-joint tests and their interpretation are necessarily more complex than bulk adhesive studies. 

Additions of reactive elements (RE), such as Y, Hf and Zr, to MCrAlY bond coats enhance the oxide adhesion. Y and Hf promote the formation of... 

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