Study on benzoxazine-based film adhesive and its adhesion properties with CFPR composites

In this paper, a benzoxazine-based (BZ) adhesive with high temperature resistant was developed by blending benzoxazine monomer and tetrafonctional epoxy monomer as matrix modifier and polyetherimide as toughening agent. The results show that benzoxazine-based film adhesive could be cured at 190 °C, and the cured film adhesive exhibited high temperature resistance and a high glass transition temperature of 224 °C. The 5% weight loss temperature in air was 400 °C and the char yield in nitrogen at 800 °C was 48%. The cured film adhesive has good ablation resistance. The fabricated benzoxazine-based film adhesive has high adhesion reliability, with single-lap shear strength of 23.20, 28.36 and 20.04 MPa at room temperature, 140 and 175 °C respectively. The curing process of the film adhesive matches well with that of carbon fiber reinforced BZ prepreg and the film adhesive has stable adhesion properties. Its biggest advantage is that, during storage and transportation, there is no need of refrigeration. After 60 days of storage for benzoxazine-based film adhesive at room temperature, its process performance and adhesion properties remain unchanged. It is expected that the benzoxazine-based film adhesive can be used in aerospace, high-speed rail and other applications.     

Influence of substrate treatment on the tribological properties of DLC coatings

Due to the very thin nature of DLC coatings, the substrate must carry the main part of the applied load. If the substrate has insufficient strength to carry the contact load and thus support the coating, plastic deformation will occur, leading to premature failure of the coating. The challenge to improve the properties of hard DLC coatings by thermo-chemical pre-treatment of the substrate has gained much attention in recent years, leading to a new method called duplex treatment. In the present study, a hydrogen-free hard carbon coating deposited on plasma nitrided AISI 4140 steel was investigated with respect to microhardness, residual stress, scratch adhesion and dry sliding wear resistance. The pin-on-disc results showed that nitriding of the substrate improves the wear resistance of the hydrogen-free hard carbon coating as compared to the hardened substrate. The improvement can be related to the increased load carrying capacity of the steel substrate and to improved coating to substrate adhesion.     

不锈钢表面电化学磷化及膜层性能

采用由4.0 g/L ZnO、4 g/L CaCl₂、5%(体积分数)H₃PO₃、4 g/L酒石酸和3 g/L氯酸钠组成的锌钙系磷化液,在温度为70°C和电流密度为4 mA/cm²的条件下对1Cr₁₈Ni₉Ti不锈钢表面进行电化学磷化20 min。对比了所得磷化膜与采用相同磷化液化学磷化2 h所得膜层的表面形貌、相结构和耐蚀性。结果表明,与化学磷化相比,电化学磷化所需时间较短,所得膜层的结晶大小和分布均匀,耐腐蚀性更好。     

琳得科将上市蓝光光盘覆盖层薄膜与粘合设备

从事粘合及粘接相关产品的琳得科日前成功开发出了面向新一代光盘规格“蓝光光盘”的厚0.1mm的薄膜(琳得科新闻发布)。将以光盘厂商等为对象销售。 蓝光光盘的一般构造为1.1mm厚的光盘底板上覆盖一层0.1mm的透明覆盖层,此次     

Role of transfer layer on tribological properties of nanocrystalline diamond nanowire film sliding against alumina allotropes

The tribological properties of nanocrystalline diamond nanowire (DNW) film treated in CH₄ atmosphere at 400 °C were studied in ambient atmosphere at room temperature using various allotropes of alumina ball as sliding counterbodies. Super low value of friction coefficient (~ 0.003) and extremely high wear resistance (~ 2.8 × 10^− 21 mm³/Nm) were observed when the Al₂O₃ ball slides against the film. In contrast, high friction coefficients with the values ~ 0.06 and ~ 0.07 were observed while using sapphire and ruby balls, respectively. Wear loss was also high ~ 4 × 10^− 19 mm³/Nm and 2.8 × 10^− 15 mm³/Nm in DNW/sapphire and DNW/ruby sliding pairs, respectively. Such a behavior is fundamentally explained in terms of the chemical nature of the sliding interfaces and surface energy of ball counterbodies. As a consequence, the chemical affinity of Al₂O₃ ball towards the carbon atoms is less, which resulted in the absence of carbonaceous transfer layer formation on the Al₂O₃ ball scar. However, in the case of sapphire and ruby balls, the wear track was found to be highly deformed and significant development of carbonaceous transfer layer was observed on respective ball scars. This phenomenon involving transfer layer formation is related to high surface energy and strong chemical affinities of sapphire and ruby balls towards carbon atoms. In such a condition, sliding occurs between film and the carbonaceous transfer layer formed on the ball exhibiting high energy due to covalent carbon bonds that chemically interact and enhance sliding resistance.     

Characterization of thick and soft DLC coatings deposited on plasma nitrided austenitic stainless steel

Thick and soft a-C:H:Si coatings containing more than 45% hydrogen (thickness: 25–27 μm, hardness: 6 GPa, Young's Modulus 38 GPa and low ratio of sp³ bonds) were deposited by PACVD with a DC pulsed discharge on nitrided (duplex sample) and non-nitrided austenitic stainless steel (coated sample). After deposition, the chemical, microstructural and tribological properties were studied. Finally, the adhesion and the atmospheric corrosion resistance of a-C:H:Si coatings were also investigated.In pin-on-disk tests, the friction coefficient using an alumina pin of 6 mm in diameter as counterpart, under 0.59 GPa Hertzian pressure was 0.05 for the coated samples and 0.076 for the duplex samples. These values were more than one order of magnitude smaller than the friction coefficient of the nitrided sample without coating, which was around 0.65. In the coated samples, the wear loss could not be measured. In ball-on-disk tests under dry sliding conditions, the coatings were tested under different Hertzian pressures (1.29, 1.44 and 1.57 GPa) using a steel ball with a diameter of 1.5 mm as counterpart. Using a normal load of 9 N, the a-C:H:Si coating of the coated samples was broken and detached thus leading to a coefficient of friction of around 0.429. However, in contrast to that, the friction coefficient of the duplex samples remained stable and reached as maximum a value of 0.208.In abrasive tests, mass loss was undetectable in both duplex and coated samples. Furthermore it could be seen that the a-C:H:Si film showed only some smaller grooves and no severe damage or deformation. On the contrary, severe damage was observed in the only nitrided sample. With respect to adhesion, the critical load to break the coating was higher in the duplex sample (27 N) than in the only coated sample (16.3 N). By chemical analysis using the salt spray fog test, the duplex sample remained clean, but the coated sample failed and presented film delamination as well as general corrosion.     

Preparation of a modified phosphate-based adhesive and its hot bonding performance on 316L stainless steel

In this study, a novel phosphate-based adhesive was prepared by using homemade aluminum phosphate as a matrix and by adding different fillers simultaneously. The effects of calcination temperature and filler composition on the bonding mechanism and high-temperature bonding strength of the adhesive for high-temperature alloys were studied. The results indicated that the crystalline transformation of AlPO₄ occurred at 500 °C. AlPO₄ has two crystalline forms at 500 °C: orthorhombic and hexagonal. The addition of CuO to the fillers resulted in the exchange of Fe and Cu at the substrate interface and enhanced the high-temperature bonding strength of the specimens. The maximum tensile strength of the specimens reached 3.9 MPa at 500 °C. These composites have potential applications in aviation, aerospace, and other fields.     

Deposition of DLC film from adamantane by using pulsed discharge plasma CVD

Diamond like carbon films are deposited on silicon and quartz substrates using adamantane as a sole source of carbon by pulsed discharge plasma chemical vapor deposition. Tauc band gap of such films has been successfully tuned from 1.7eV to 2.9eV. Iodine incorporation is observed to favor the growth of such films and induces disorder in the films. It also brings down in energy the on-set of photon absorption. Such iodine incorporated diamond like carbon films may be interesting candidates for the new coming applications such as for heterojunction photovoltaic devices.     

Corrosion and tribological properties of ultra-thin DLC films with different nitrogen contents in magnetic recording media

The corrosion spot density and contact–start–stop tribological properties that correlate to mechanical properties, electrical resistivity and lubricant bonded ratio of DLC overcoats on different disks of various surface roughness were investigated. DLC overcoats of hydrogenated carbon (CH) and nitrogenated carbon (CN) films were deposited by ion beam deposition (IBD) and sputter, respectively. Results show that the intensity ratio I(D)/I(G) increases with decreasing IBD-CH film thickness and increasing N₂ concentration of sputtered-CN layer, which implies that the films prepared at higher N₂ concentration contain a relatively lower sp³ bonded carbon. The composite hardness and Young's modulus of DLC films decrease with decreasing IBD-CH thickness and increasing N₂ concentration of sputtered-CN layers. Compared to disk overcoats deposited with only IBD-CH of comparable thickness, the lubricant bonded ratio is dramatically increased from 12 to 30% when the 0.5 nm CN is deposited on IBD-CH film. By increasing the N₂ concentration in the CN layer from 10 to 50 at.%, the electrical resistivity decreased from 3.6 to 0.8 kΩ and the lubricant bonded ratio increased from 30 to 46%. The corrosion spots density of sputtered-CN film surface decreases with increasing N₂ concentration. It is concluded that the dual layer of 1.5 nm IBD-CH/0.5 nm sputtered-CN with 30% N₂ deposition has the best integrated performance of corrosion resistance and CSS tribological properties.     

Tribological properties of DLC films deposited on steel substrate with various surface roughness

Tribological properties of diamond-like carbon (DLC) films in water were investigated concerning with the influence of surface roughness and various mating materials. The DLC films were deposited by pulsed-bias CVD method on AISI630 stainless steel. The substrate roughness (R_a) is in the range of 1.4–740 nm. AISI 440C, AISI 304 stainless steel and brass balls were used as a mating ball. The friction coefficients of DLC films against with AISI 440C stainless steel ball indicated under 0.1 irrespective of the roughness. The film having smooth surface (R_a=1.4 nm) had severe damage at a load of 9.4 N. However, the film having rough surface (R_a=263 nm) had no damage at the same load. The specific wear rate of the steel ball increased with increase of roughness of the surface. In the case of AISI 304 stainless steel ball, the specific wear rate of the ball showed similar tendency. The friction with brass ball showed relatively high friction coefficient in the range of 0.12–0.25. However, the damage on the films could not be observed after friction test. It is considered that the roughness of the surface is important factor for the rupture of the film in water environment.     

Tribocorrosion and corrosion behavior of stainless steel coated with DLC films in ethanol with different concentrations of water

There has been a recent increase in both the production and consumption of ethanol due to the numerous environmental advantages that it offers, such as the fact that it can be produced from a variety of renewable materials, for instance corn and cellulose, or it can be obtained from sugarcane bagasse and biomass (2nd and 3rd generation ethanol). The result of this is that nowadays ethanol is widely seen as the dominant biofuel – or as a blend component in gasoline or pure fuel - in many countries.However, one disadvantage of the use of ethanol is the high corrosive behavior that occurs when its hygroscopic properties are exposed to a large number of materials. Xiaoyuan Lou and Preet Singh showed that the increase of water concentration in ethanol induces pitting and metal loss. Diamond-Like Carbon (DLC) films may be a solution to this problem due to the fact that they can be deposited inside tubes, offer good protection levels against corrosion, and reduce the friction coefficient and wear.This paper shows the tribocorrosion and corrosion studies of DLC films deposited on stainless steel grade 304 (SS304) substrates in order to gauge its appropriateness usage in the construction of pipelines and fuel storage tanks. The surface morphology was analyzed before and after 14 days of immersion. The tribocorrosion, friction coefficient, and wear rate were studied in ethanol to see the effects of water concentration. The films showed good adherence to the substrates. Corrosion and tribocorrosion results showed that for bare Stainless Steel 304 the increase of the water content increases the corrosion and the friction coefficient. DLC coated samples presented few points of delamination, and the friction coefficient and open circuit potentials were very low compared with the bare sample which was water concentration independent.     

Structure and properties of Si and N co-doping on DLC film corrosion resistance

Three species of diamond-like carbon (DLC) film were systematically examined in NaCl solution for their anticorrosion properties. Si&N&H-DLC has better electrochemical characteristics and salt spray corrosion testing results than the substrate and two species DLC films in NaCl solution. Due to the successive growth of Si, N, and H-DLC, there is a well-bonded Si–N interface and the formation of Si oxides. The Si&N&H-DLC film exhibits extremely high charge transfer resistance, exceeding 10⁶ Ω/cm². A salt spray test shows that the Si&N&H-DLC film presents a lower rate in NaCl solution in comparison to the substrate and the other two species of DLC films. As a result, the Si&N&H-DLC film significantly improved the corrosion performance of the substrate.     

不锈钢表面有机-无机复合膜的制备及其抗海水腐蚀性能

以多巴胺修饰304不锈钢为基体,采用溶胶凝胶法和自组装成膜法制备了SiO2基、TiO2基和SiO2-TiO2混合基有机-无机杂化涂层。探讨了钛酸四丁酯、正硅酸乙酯和11-巯基十一烷酸(MUA)在不锈钢基体上的成膜性和成膜后的抗腐蚀性能。借助金相显微镜观察了不锈钢基体上的杂化膜的显微形貌,塔菲尔曲线和电化学阻抗谱对比分析了杂化膜的抗腐蚀性能。结果表明,MUA和TiO2、SiO2能复合成膜,膜的致密性好,具有可重复性,且引入TiO2和SiO2后,其抗腐蚀性能有较大幅度提高。     

Surface treatment of AM355 stainless steel for adhesive bonding

Surface treatments for preparing AM355 stainless steel for adhesive bonding have been studied. Lap shear, wedge test and stress durability data are presented for bonds prepared using 19 different surface treatments. The oxides formed on the stainless steel as a result of the surface treaments have been characterized using Auger electron spectroscopy, X-ray photoelectron spectroscopy, ellipsometry, and surface potential difference, photoelectron emission and water contact angle methods.     

Ultrasonic testing for bond efficiency of carbon steel to stainless steel adhesive joints

Structural adhesive joints between carbon steel and stainless steel were made and evaluated. Various combinations of a two-component epoxy adhesive were used and diverse polymerization cycles were employed to obtain joints of different mechanical strengths. Two ultrasonic procedures were used: ultrasonic scanning with a focused beam to ascertain the quality and the uniformity of the joints; and ultrasonic spectrum analysis to evaluate bond strength. The influence on adhesion of surface calamine of the carbon steel was also investigated: bond strengths were comparable with those attained with ground carbon steel adherends. Adding lubricating oil to the adhesive was found to increase the mechanical properties of the joints.     

Nucleation and growth of amorphous carbon film on tungsten-implanted stainless steel substrates

Amorphous carbon (a-C) films were deposited on W-implanted (20 kV, 3 × 10¹⁷ ions cm^− 2) and un-implanted steel substrates by plasma immersion ion implantation and deposition (PIII&D). The W implantation pretreatment changes the surface structure and impacts film nucleation. Consequently, the growth mechanism of the a-C film is altered resulting in different surface morphologies and roughnesses even though the films deposited on the un-implanted steel substrates possess similar a-C structures as revealed by Raman spectroscopy. The structural differences are probed by X-ray photoelectron spectroscopy and X-ray diffraction. Moreover, microstructural observations were carried out by transmission electron microscopy. A model based on the statistical formation theory is proposed to explain the growth of the a-C films on the implanted and un-implanted substrates.     

A study of the solid salt film on nickel and stainless steel

During steady state diffusion controlled dissolution of one-dimensional pit electrodes of stainless steel SS 302 and nickel, impedance and transient measurements were carried out to determine the ohmic potential drop across the salt film Δε_ΩF, the electric conductivity of the film σ_F and the film thickness d_F as a function of potential and solution composition. It was found that Δε_ΩF increases with decreasing diffusion limited current density, i_p, and with potential. For i_p → 0 it approaches a value which is independent on the bulk concentration. The critical potential for salt film formation is −0.9 and −0.08 V vs sce for SS 302 and nickel, respectively. The specific electric conductivity of the salt films is approximately 1.4 × 10⁻⁵ and 4.4 × 10⁻⁵ S cm⁻¹ for SS 302 and nickel, respectively. The salt film thickness linearly increases with potential and bulk concentration and is very thin compared to the pit depth (less than 1.5% at potentials < 1.2 V vs sce and chloride concentrations < 6 moll⁻¹).     

改性环氧底胶对不锈钢与聚氨酯橡胶粘接的影响

研制出改性环氧胶粘剂作为底胶用于不锈钢与浇注型聚氨酯橡胶的粘接。试验结果表明,该胶粘剂具有较高的粘接强度,粘接处经受０￣４．３ＭＰａ的循环水压测试而无漏水现象发生,满足了技术要求并通过了应用验证试验。     

EIS study of potentiostatically formed passive film on 304 stainless steel

Passive film was potentiostatically grown on Type 304 stainless steel at potentials between −0.4 and 0.3 V vs. Hg/HgSO₄ in 50 mV intervals. Electrochemical impedance spectroscopy was used to study properties of the grown passive films. Relevant circuit analogs were selected to fit the electrochemical impedance data obtained at each potential. The resultant parameters were used to calculate film thickness through both film capacitance and resistance. The calculated thicknesses were compared with ellipsometry thickness measurement results. An overestimation occurred when the film resistance was used to calculate the film thickness. On the other hand, when the CPE parameter Q was used, the film thickness was underestimated. Available approaches were employed to calculate the effective capacitance of the film. A comparison between the film thickness calculated from the effective capacitance and ellipsometry measurements suggested a surface distribution of time constants on the surface.