Surface Treatment Of Adherends Research Articles

Environmentally assisted crack growth in adhesively bonded composite joints

Adhesively bonding composite components is a reliable alternative to conventional joining processes that minimizes part weight and reduces fabrication costs. Regarding performance and reliability, of particular interest is developing adherend surface treatments that enhance adhesion of the joint interfaces in aggressive chemical environments. Using fracture mechanics-based adhesion metrologies, critical and subcritical crack growth were evaluated for several peel-ply-treated, adhesively bonded composite joints. Fracture toughness, Gc, and corresponding failure modes were evaluated for specimens constructed using two different bonding processes (co-bonding and secondary bonding) and four different peel ply treatments. Environmentally assisted crack growth was evaluated as a function of time in several environments: humid, high temperature humid, and hydraulic fluid immersion. It is shown that humid environments accelerate crack growth rates, da/dt, relative to the strain energy release rate, G. This effect was amplified at elevated temperatures and further amplified in the presence of hydraulic fluid.

Influence of Surface Treatment of Steel Adherends on Shear Strength of Filled Resins

Adhesion of resins and adhesives to adherend is one of the important characteristics, including the area where the resin or adhesive is filled with particulate fillers in order to optimize this adhesion, achieve other mechanical characteristics or in order to reduce the price of the resulting resin or adhesive. When discussing filled resins with particulate fillers, these materials can be defined as a polymer composite systems. Surface treatment of adherend before applying such a filled resin, is crucial to the overall strength of this interface. Blasting is commonly used kind of surface treatment of metal adherends. Properly chosen blasting conditions and achieved roughness parameters are crucial to the overall strength. The experiment describes the impact of the changing conditions of blasting on the shear strength of epoxy resins filled with glass powder. The results of the experiment show that the highest shear strength on steel adherend was achieved when the surface was blasted at an angle of 60 - 90° (12.93 ± 0.62 MPa). The roughness parameters Ra and Rz were influenced by a specific kind of blasting material (Al2O3 F80 and glass beads B10), which has also a considerable influence on shear strength.

Effects of various adherend surface treatments on fatigue behavior of joints bonded with a silver-filled electronically conductive adhesive

Conductive adhesives have been used in a variety of electronic packaging applications. This paper presents an investigation into the effects of various adherend surface treatments on the fatigue and failure behaviors of adhesively-bonded joints. For this purpose, single-lap joints were fabricated using specimens with adherend surfaces modified employing various chemical and mechanical modification techniques, and tested under a spectrum of fatigue and environmental conditions. The results of our work indicate a profound influence of the adherend surface on both the fatigue behavior and also the moisture ingress mechanism into the joint. Finally, experiments were conducted to assess the effect of adherend surface condition on the moisture ingress mechanism.

Metal-Polymer Interphases in Structural Adhesive Joints

AbstractHigh-performance structural adhesive joints, such as those found in aerospace components, must exhibit both high initial strength and excellent durability in severe environments. These properties are largely governed by the bonding across and the stability of the metal (oxide) - polymer interphase. Modern adherend surface treatments commonly provide the required adequate strength and durability. Factors that can degrade or limit joint strength and durability are discussed along with means to improve or, at least, to prevent reduction of these properties. Finally, areas in which advances are needed: increased understanding of bonding phenomena, improved reliability of bonded joints, and minimized environmental burdens are suggested.

Evaluation of some machining processes as adherend surface treatments in bonding aluminium

—This paper reports detailed studies on some machining processes used as adherend surface preparation methods. The two conventional treatments of sand blasting and chromic-sulphuric acid etching were also studied to compare their relative merits in making strong bonds. The nature of the adherend surface produced by these processes was examined by electron microscopy and surface profile records to determine its significance in the bonding process. Aluminium alloy 2014 (untempered) was used as the adherend material and a heat-curing, two-part structural epoxy as the adhesive. It was observed that different treatments render different bond strengths, and that variation of some process parameters in each treatment influences the joint strength with the same adhesive-adherend system. The surface profile records and electron micrographs of the treated adherends give an indication of the relative bond strengths which occur after the joints are formed. Some machining processes such as shaping, milling, and turnin...

A three-point flexure test configuration for improved sensitivity to metal/ adhesive interfacial phenomena

Abstract A three-point flexure test was used to evaluate the effects of chemical surface treatments on the performance of adhesively-bonded structures of Ti6A14V. A single adherend/adhesive structure rather than a double adherend sandwich configuration is shown to be sensitive to pre-bonding adherend surface treatments. Data is presented which relates mechanical properties with chemically treated adherend surfaces. Photoelastic isochromatic fringes were recorded simultaneously with the flexure test as a means to monitor stress distribution, failure initiation, and crack propagation.