Applied Adhesion Science最新文献

This paper is intended to demonstrate how the parameters for the surface preparation of magnesium alloys for adhesive bonding can be optimized. The effects of different laser parameters are analyzed by using a combination of advanced sample preparation and ultra-high resolution scanning electron microscopy on a nanoscale level and a specific combination of mechanical tests on the macroscopic level. These data allow a discussion of the physical principles and the key parameters influencing the interaction of laser radiation with the magnesium surface.

To a certain extent, adhesive bonding of measurement equipment is very common in science and technology, e.g. adhesive bonding of small-scale strain gauges. Adhesive bonding of the entire equipment for a fully autonomous pile driving monitoring of an impact-driven large-scale foundation structure for an offshore wind farm is a completely new application method. Several offshore wind farms are currently under construction in the North and Baltic Seas. Impact pile driving of the large-scale foundations usually causes much louder noise than permitted by regulations, so methods for noise reduction are necessary. Geotechnical engineers of the TU Braunschweig are investigating combined methods for reducing that noise, and in 2014 they had the opportunity to install measurement equipment for the investigation of dynamic pile deflections during pile driving into three of in total eighty monopiles (length: 60?m, diameter: 6?m) of an offshore wind farm in the German North Sea. Due to certification issues conventional methods of fastening such as screwing or welding were not permitted. Instead, adhesive bonding of all parts (sensors, cables, shielding, recorder/computer) was successfully applied and withstood impact driving with several thousand blows of up to 1200?g (earth gravity). The authors would like to present the concept and preceding tests of the adhesive bonding applied within the research project ‘triad’.

In this study, the failure strengths of adhesively bonded joints were investigated. The glass fiber epoxy composites used as adherends were manufactured by using vacuum assisted resin infusion method (VARIM). The adhesively joint materials were Loctite-9466 and DP-460 as a brittle and ductile material, respectively. Since the strengths of these materials are close to each other under static loading, the applied axial energies were determined using different levels of 5, 10, 15 and 20 Joules. In order to determine the energy characteristics of the experiments, axial impact loadings were applied as both single and repeated three times under the same conditions. The results showed that the failure strengths of these two different adhesives of Loctite-9466 and DP460 changed depending on single and three times repeated axial impact loadings. This paper is intended to give an overview between ductile and brittle adhesives under both single and repeated impacts. In addition, it will help for designers who need information on mechanical properties of ductile and brittle adhesives under single and repeated impacts.

The effects of the increase in temperature are of great importance when evaluating the strength of an adhesive. Some processes in mining, such as copper electro-wining, produce thermal changes that modify the working conditions of equipment and structures; these elements are exposed to temperatures that can reach up to 80?°C. The study presented here aims to determine the behavior, under fracture of mode I type, of a two-component adhesive regularly used to join pieces in acid mist extraction systems. For this purpose, specimens for a double cantilever beam test were produced and tested in an Instron tensile machine, which includes an environmental chamber to control the test temperature; each lot of specimens was tested at 20, 50 and 80?°C respectively, at a speed of 1?mm/min. From the results obtained, it is possible to appreciate that the adhesive at 50?°C decreased its strength by 14?% with respect to those at the reference temperature of 20?°C. The same tendency was observed in the specimens tested at 80?°C, in which there was a pronounced reduction in strength quantified by 26?%. Moreover, deformation in the adhesive grew with the increase in temperature, acquiring greater plasticity and modifying its cohesive properties.

The aim of this study was to evaluate the shear bond strength (SBS) of three different cements to zirconia and lithium disilicate ceramic surface after thermal cycling. Thirty zirconia (Z) and thirty lithium disilicate (L) disk specimens were prepared in 8?mm in diameter and 3.4?mm in thickness from zirconia and lithium disilicate ceramic blocks. Each group was divided into three subgroups (n:10). The specimens from all groups were bonded with three different cements using transparent polyethylene tubes: Zn-Phosphate cement (ZPC); self-adhesive resin cement (SARC); adhesive resin cement (ARS). The specimens were then subjected to thermal aging procedure for 1?week under 37?°C water bath. Shear bond strength (SBS) was determined using a universal testing machine at a crosshead speed of 1?mm/min. The specimens were also examined both with a scanning electron microscope (SEM) and a stereomicroscope. Statistical analysis was performed with one-way ANOVA. Pair-wise statistical comparison was made with Tukey test. The overall significance level was set at α?=?0.05. For the tested groups, the SBS values ranged from 0.29?±?0.03 to 12.10?±?0.25?MPa. L-SARC group yielded the highest SBS value (p?<?0.05) among the groups, while Z-ZPC group had the lowest (p?<?0.05). Significantly higher SBS values were found for all the groups of lithium disilicate disk specimens (L) when compared to those of zirconia disk specimens (Z) (p?<?0.05). Tukey’s pairwise comparisons revealed that SBS values of SARC groups were significantly higher than those of the ARC and ZPC groups (p?<?0.05). Mode of failure analysis results showed that, the modes of failures were mixed with adhesive debonding predominantly with minimal resin residues (<10?%) for SARC groups. However, the other groups showed adhesive failure predominantly. Within the limitation of this in vitro study, it was concluded that selfadhesive resin cement had the highest shear bond strength values when bonded to lithium disilicate and zirconia ceramic surface. However zinc-phosphate cement demonstrated significantly lower shear bond strength values for both ceramic groups.

The influence of the presence of copper on the network formation and the surface chemistry of an epoxy acrylate based solder mask system were investigated, with regards to the application of solder masks on copper layer. The presence of copper within the bulk volume of the solder mask was characterized by utilizing scanning electron microscopy/focused ion beam and energy dispersive X-ray analysis. The copper originates from the copper layer underneath and decreases towards the surface. Differences in the network structure were analyzed by applying infrared spectroscopy in attenuated total reflection mode, which showed no changes in the network structure due to a copper layer underneath. The surface chemistry of two solder masks with different curing agents, amine and anhydride, was investigated for differences caused by changes in the curing behavior depending on copper complex formation. Surface chemistry was analyzed by applying X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry. Measurable differences in the surface chemistry with regards to copper content are generated due to the copper layer underneath. However, through the optical contact angle method and pull-off test, no differences concerning wetting or adhesion behavior between the solder mask and an epoxy adhesive were observed.

This paper introduces a new type of peel tests dedicated to composite bonding: Composite Peel Tests. This test is inspired on the standard floating roller peel test widely used for metal bonding.

The aim of this study is to investigate the potential of the Composite Peel Test to assess interface adhesion in composite bonded structures. To this end, peel tests were performed with nine different types of adhesives and at two environmental temperatures, room temperature and +80°C. The results were compared with the standard floating roller peel tests with Aluminium adherends.

The results show that when using the Composite Peel Test good interface adhesion results either in cohesive failure of the adhesive or intra-laminar failure of the composite, while bad adhesion results in adhesive failure. In most cases of good interface adhesion, increasing the temperature favors cohesive failure of the adhesive in detriment of intra-laminar failure of the composite.

Peel strengths can be used as a quality indicator of interface adhesion only if using exactly the same type of flexible adherend (peeling-off member). Nevertheless, if cohesive failure is the dominant failure mode, the comparison between adhesives’ peel strength is consistent disregarding of the type of peel-off adherend. Composite Peel Tests are suitable to assess interface adhesion of composite bonded structures.