Adhesion studies of radio-frequency sputtered SiO2 films on Ti,stainless steel,Ni and Inconel substrates. Effects of substrate surface ion bombardment etching

The scratch test was applied to determine the adhesion strength of radio-frequency (RF) sputtered SiO₂ films to Ti, stainless steel, Ni and Inconel substrates. The effect of substrate ion bombardment etching was investigated by using a mean critical load derived from a Weibull-like statistical analysis. It was found that the mean critical load values obtained on substrates etched by ion bombardment for a sufficiently long time were two to three times those obtained on mechanically polished substrates. Scratch tracks were observed by scanning electron microscopy and some X-ray spectra were measured after the electron beam of the scanning electron microscope was focused inside the scratch channel. Depth composition profiles were also recorded by Auger electron spectroscopy. No important presence of contamination was observed in the interfacial domain even after mechanical polishing, but the width of this interfacial domain was higher after ion bombardment than after mechanical polishing. This difference in width could result from the formation of microcavities and vacancies at the substrate surface during ion bombardment. In such a case, the significant adhesion improvement should principally occur from an enhanced interlocking of the coating to its substrate.     

Adhesion enhancement of thin copper film on polyimide modified by oxygen reactive ion beam etching

Polyimide (PI) films were modified by O₂ reactive ion beam etching (RIBE) to enhance the adhesion of subsequently deposited copper films. The adhesion of evaporated copper on the O₂ RIBE-modified PI consisted of three different regimes. The first regime involved chemical reaction between PI and Cu atoms; the second regime involved the mechanical interlocking of the grass-like structure of the modified PI with Cu; and in the third regime, overetching was observed. The locus of failure was also analyzed to understand the adhesion mechanism of Cu on the PI. A 10% decrease in adhesion strength was observed after thermal cycling. Furthermore, humidity tests showed that the adhesion enhancement by mechanical interlocking of the grass-like structure is not affected by the presence of moisture.     

Effects of substrate bias voltage on adhesion of DC magnetron-sputtered copper films on E24 carbon steel: investigations by Auger electron spectroscopy

The adhesion strength of copper thin films on E24 carbon steel substrates was studied using the scratch test via the critical load. Coatings were deposited by a DC magnetron sputtering system. All substrates were mechanically polished; some of them were directly coated and others were ion-etched by argon ions prior to deposition process. The effects of substrate negative bias voltage during the film growth were investigated. Experimental results showed that the critical load depended on the bias voltage and that the higher bias voltage, the better adhesion. It was also observed that the deposition rate of deposited films gradually decreased with the increase of the substrate bias voltage. Furthermore, the working pressure during the substrate ion bombardment etching greatly affected the critical load. Scanning electron microscopy was used to observe the scratch tracks to accurately evaluate the critical load. Substrate surface profiles obtained by a mechanical profilometer showed that the critical load increased with the increase of the surface roughness. The analysis by Auger electron spectroscopy revealed that the interface, in case of an unbiased substrate, was relatively narrow and abrupt. However, in case of a bias voltage application, the interface was wider and more diffuse. These results suggest that the mechanisms involved in critical load enhancement are due firstly to the substrate surface roughness and the substrate temperature generated by the ion bombardment, secondly to the physical mixing in the interfacial domain and the densification of the deposited material created by the bias voltage.     

拉开测试法评定机械镀锌层的结合强度

分别采用划格法和拉开法测量了机械镀锌层与A3钢片的结合强度。结果表明:划格法只能定性地对镀层结合性能进行评价,其结果不能准确反映镀层的结合强度;拉开法则能较准确地定量反映镀层的结合强度,且随着镀层厚度的增加,镀层结合强度呈下降趋势。     

纳米颗粒对环氧树脂胶粘剂／钢铁附着强度的影响

采用纳米Al2O3、纳米CaCO3、纳米SiO2三种纳米颗粒,机械混合对环氧树脂胶粘剂进行改性,并对纳米颗粒改性的环氧树脂胶粘试样进行了附着强度的检测。结果发现,通过改变纳米颗粒的种类和含量,环氧胶粘剂／钢铁基体之间的附着强度得到不同程度的提高,其中添加2％纳米Al2O3颗粒的环氧胶粘剂与钢铁基体的附着强度提高了4倍左右。通过断面形貌特征和不同基体粗糙度下对添加纳米颗粒环氧胶与钢铁基体之间附着强度的检测,对此现象产生的原因进行了分析和讨论。     

Surface modification of ultra-high strength polyethylene fibers for enhanced adhesion to epoxy resins using intense pulsed high-power ion beam

The effects of intense pulsed high power ion beam (HPIB) treatment of ultra-high strength polyethylene (UHSPE) fibers on the fiber/epoxy resin interface strength were studied. For this study, argon ions were used to treat Spectra? 1000 (UHSPE) fibers in vacuum. Chemical and topographical changes of the fiber surfaces were characterized using Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), dynamic wettability measurements, and scanning electron microscopy (SEM). The fiber/epoxy resin interfacial shear strength (IFSS) was evaluated by the single fiber pull-out test. The FTIR-ATR and XPS data indicate that oxygen was incorporated onto the fiber surface as a result of the HPIB treatment. The wettability data indicate that the fibers became more polar after HPIB treatment and also more wettable. Although the total surface energy increased only slightly after treatment, the dispersive component decreased significantly while the acid-base component increased by a similar amount. SEM photomicrographs revealed that the surface roughness of the fibers increased following the HPIB treatment. The single fiber pull-out test results indicate that HPIB treatment significantly improved the IFSS of UHSPE fibers with epoxy resin. This enhancement in IFSS is attributed to increased roughness of the fiber surface resulting in mechanical bonding and in increased interface area, increased polar nature and wettability, and an improvement in the acid-base component of the surface energy after the HPIB treatment.