Effect of silane hybrid modification on the distribution of etched tunnels in aluminum foils

Effects of aluminium surface morphology and chemical modification on wettability

A facile solution-immersion process for the fabrication of superhydrophobic gibbsite films with a binary micro-nano structure: Effective factors optimization via Taguchi method

The effect of surface modification on initial ice formation on aluminum surfaces

Effects of modification of palygorskite on superamphiphobicity and microstructure of palygorskite@fluorinated polysiloxane superamphiphobic coatings

As the first step of the research project, elements made of medium density fiberboard (MDF) were subjected to thermal modification in a laboratory dryer (temperature: 160, 170, 180 and 190°C; time of primary modification: 0·5, 1·0 and 1·5 h) in an atmosphere of hot air or limited contact with air. Half of the total set of samples were covered with aluminum foil to cut them off from oxygen. After the modification, samples were soaked in water to determine swelling and find optimal parameters from the point of view of reduction of MDF swelling. The samples were thermally modified using the following parameters: temperature of 180°C, time of primary modification of 0·5 h and full contact of the modified MDF with hot air. Some of the modified samples, which were still hot at the end of the primary process of modification, were cold pressed to obtain higher density MDF. Tests on the mechanical and physical properties of this material were carried out to investigate the effects of combined thermal modification and densification on MDF properties. The modulus of rupture and modulus of elasticity in bending, thickness swelling, Brinell hardness and color changes were determined according to EN 310, EN 317, EN 1534 and EN 7224. Thermal properties of the thermally modified MDF and densified MDF were determined using a portable heat transfer analyser.

Effect of surface and contact points modification on the output performance of triboelectric nanogenerator

Advanced engineered composites are being increasingly in demand to increase the strength-to-weight ratio for structural performance in automobile and aerospace components for reducing fuel consumption and gas emission. Hybrid composites/laminates using lightweight metal and plastics are one of the emerging trends to create such structures. The number of methods for controlling the joints of metal and plastic interface in laminate structure has been opened for research. The present study endeavors toward the effect of surface modification of the metal skin on the adhesion strength between metal skin and polymer composite core. A laminate structure with aluminum skin and epoxy-expanded polystyrene (EPS) composite was developed. The surface modification on the surface of aluminum sheet was done using sand and glass bead blasting at various pressures (3, 4, 5, 6, and 7 bar). The effect of blasting pressure and blasting medium on the adhesion strength of the laminate structure was studied. The adhesion strength between the laminate structures was observed to be improved at the optimal blasting pressure of 5 bar blasted using SS sand.

The success of the rechargeable Li-S cell is limited in part by the dissolution of lithium-polysulfide in the electrolyte. Remarkably, it is found that removal of the conventional membrane separator in a Li-S cell improves sulfur utilization and cycling performance, whether the sulfur is initially contained in the cathode or electrolyte. An optimized cell design yields discharge capacities as high as 980 mA h g-1 after 100 cycles.

The strength of an adhesive joint is not a property of the adhesive alone but is a system property depending on adherends, the adhesive, the joint geometry, and service (or test) conditions. Most standard test methods specify giving the results as an average stress at failure. Use of this average stress is not very useful in the design and prediction of the strength of other adhesive joints that differ in even slight detail from the geometry of the test specimen. On the other hand, fracture mechanics methods have shown real promise in quantitatively explaining how differences in geometry can affect joint strength. The effects of modifications of lap specimens, similar to those described in ASTM D3165 ‘Strength Properties of Adhesives in Shear by Tension Loading of Laminated Assemblies’ have been investigated. An earlier paper discussed changes in strength resulting from tapering of the adherends over the overlap region. Here this type of analysis is extended to lap joints in which large debond regions were introduced in the adhesive joint. In both cases, the finite element/fracture mechanics predictions were in good agreement with experimental observations on steel-epoxy lap specimens. Next, a study of failure in cleavage specimens is discussed. ASTM D3433 ‘Fracture Strength in Cleavage of Adhesives in Bonded Joints’ is an ASTM standard whose basis lies in fracture mechanics. This standard makes use of specimens composed of ‘double cantilever beams’ (DCB) bonded together with the adhesive to be evaluated. The equation provided in ASTM D3433, to calculate the adhesive fracture toughness G Ic, is based on the equations from mechanics of materials for flexure stress and vertical beam shear stress and assuming ideal cantilever end conditions. This equation, therefore, neglects any energy stored in the adhesive or through rotation of the cantilever end and/or stored in the beam beyond the crack tip (assumed cantilever point). This equation was carefully analyzed using both classical (from the literature) and numerical methods. One would, of course, anticipate that the original assumptions would be most valid for long slender beams and very thin adhesives. Careful finite element/numerical analysis indicates, however, that when using dimensions well within those suggested in ASTM D3433, the energy release rate or G Ic determined including these factors can differ by more than 50% from that obtained using the recommended equation. A quasi-elastic adhesive was used with aluminum sheets to manufacture DCB specimens. A group of these specimens were tested to failure and the results used to determine a reference G Ic. This G Ic was then used with finite element methods to predict performance for test specimens with different geometries, i.e. the adhesive thickness and/or adherend thicknesses were altered. These test results confirmed the validity of the fracture mechanics/finite element approach. The calculated failure loads for the geometries typically differed by no more than 8% from the experimentally determined loads. The results for one sample lot differed by slightly more than 12% from the reference value but, as explained in the text, this difference might be attributed to mode dependence. On the other hand, use of the standard equation with the test results to calculate G Ic yielded values that differed by as much as 61650% between the different sample geometries. The finite element methods were also used to calculate the energy release rate for various assumed crack paths through the adhesive. It was hypothesized that the fracture locus should follow paths of maximum energy release rate. Experimental observations of crack paths for a number of different geometries of DCBs were consistent with these predictions in every case.

Ultrasonic cleaning is widely accepted as an invaluable tool for minimizing contamination of critical devices, particularly where complex geometries such as blind holes are present. In order to use this powerful technique effectively, it is necessary to identify multiple parameters and to optimize conditions. Optimizing ultrasonic effectiveness involves removal of undesirable contaminants. Because ultrasonic cleaning generates significant force, effectiveness also involves minimizing the potential for substrate damage. Cavitation quality, and cavitation effects, are dependent on a number of factors including the frequency, amplitude, chemistry (aqueous or solvent), time, and pressure. The negative impact of ultrasonic erosion is often assumed to be minimal, particularly where more sophisticated ultrasonic systems are employed. Where the surface itself is more complex and contains what might be termed microstructure (or nanostructure), the potential for damage during ultrasonic cleaning must not be ignored. Several examples are presented to illustrate the desirability for independent, documented studies of the impact of ultrasonic cleaning or of ultrasonic extraction on critical products. As one simple model, studies were conducted on various thicknesses of aluminum foil. Efficacy of cavitation and potential for surface modification effects was indicated by foil erosion. In a second example, loss of metal substrate from critical components (or subassemblies) used in inertial navigation systems was observed after one hour of ultrasonic extraction. Both examples involve softer metals than are typically used in biomedical devices. However, depending on the size and configuration of the device, the issue of erosion and/or stress must be considered. The potential for ultrasonic damage in miniature devices and indications of such damage is discussed. Many newer cleaning chemistries, particularly biobased chemistries, are ineffective at ambient temperature. Discussion indicating the impact of elevated temperature are included. In some cases, it appears that ultrasonic cleaning may be superfluous in certain biobased chemistries at elevated temperature. It is typically assumed that ultrasonic cleaning will be conducted at atmospheric pressure. However, many newer cleaning systems operate at reduced pressure that reduce the boiling point. Therefore, studies of cavitation effects at reduced pressure or at high temperature are discussed. Typically, extensive studies of appropriate conditions for ultrasonics are not conducted. Instead, conditions are selected based on previous pragmatic observations or on vendor recommendations. In recent years, the number of available options in ultrasonic equipment and chemistries has increased markedly. At the same time, there has been a trend toward miniaturization and increased complexity of configuration in biomedical devices; this trend means increased surface, increased potential for contamination, and increased potential for unintended surface modification. With increasing use of ultrasonics for such critical applications as medical implants, the need for additional independent studies of ultrasonic efficacy is proposed.