Surface Treatment Layer Research Articles

Study on the Corrosion Resistance Of Thermal Sprayed Aerospace Coatings Under The Action Of High Current Pulsed Electron Beam

Aluminum-based amorphous alloys have excellent mechanical properties and corrosion resistance and are currently used in the form of coating materials for the protection of aircraft surfaces. In this study, AlCoCe alloy and powder are prepared, and then AlCoCe alloy coating is prepared on Q235 substrate by supersonic flame thermal spraying technology, and finally, the surface remelting modification treatment is carried out on the coating by current pulsed electron beam, and the transformation behavior of microstructure of the coating and the change of the corrosion resistance in this process are analyzed by structural characterization and corrosion experiment, to make clear the relationship between the structure of the coating and its corrosion resistance performance. After 15 current pulsed electron beam pulses, the coating surface formed a layer of dense and homogeneous composition of the amorphous structure of the treatment layer, when the number of pulses is higher, due to the heat of the substrate leads to a decrease in the cooling rate, which in turn will lead to the emergence of a crystalline structure of the surface treatment layer.

Experimental and numerical study on improving mechanical properties of new polyurethane-emery thin polymer overlay (TPO) structure using three-point bending test

The thin polymer overlay (TPO) is a new type of road surface treatment layer for high traffic pressure and high road performance requirements. Therefore, it is not only widely used on highways but also has more and more applications in the field of bridge deck pavement. In this work, a new type of TPO—the polyurethane-emery TPO composite material was proposed, and a reasonable material mixing ratio is determined. In addition, the flexural and compressive behaviors of the polyurethane-emery TPO reinforced with the steel fiber and cement materials are investigated, and a comparison is made for the development of a numerical model to simulate the behavior of the reinforced-new-TPO using the Finite Element (FE). The experimental tests include three-point bending and compressive tests to evaluate the ultimate capacity of the new-TPO material in flexural and compression and its modulus of elasticity. Moreover, the flexural and compression performance of polyurethane-emery TPO containing different reinforcement configurations was evaluated in three-point bending and compression tests, and the reinforcing effects of different steel fibers and cement contents were investigated. The use of steel fiber and cement-reinforced thin polymer overlay in reinforced bridge surface treatment construction was found to be able to significantly offer several advantages, such as excellent corrosion resistance, and flexural and compression strength. Through experimentation, it can be seen that the new type of polyurethane-emery TPO proposed in this paper can completely replace the existing TPO, however, the effect of the dosage of steel fiber and cement needs to be considered during the design. Meanwhile, a three-dimensional nonlinear finite element model was established by using ABAQUS, which incorporated the second development model of steel fiber based on python and CDP models and can be used to predict the flexural and compression behaviors. The numerical model was experimentally validated by using the three-point bending and compression test results and was used for parametric studies. The parameters investigated in this study were steel fiber content, fiber length, and polyurethane-cement ratio of the polyurethane-emery TPO reinforcement. The proposed new polyurethane-emery TPO system was revealed to be promising for the development of the bridge surface treatment reinforcement formwork and can be used in superstructure construction for the extension of the bridge service life. The numerical and the experimental results were generally in good agreement.

Preliminary Validation of Steel Slag-Aggregate Concrete for Rigid Pavements: A Full-Scale Study

The high wear resistance and toughness of electric arc furnace slag (EAFS) means that this industrial by-product can successfully replace natural aggregate in hydraulic or bituminous concretes that withstand vehicle traffic. This article validates the use of concrete made with large amounts of EAFS for rigid pavements. Accordingly, three EAFS–concrete mixes made with metallic or synthetic fibers were designed. Their performance was studied through laboratory tests (compressive strength, modulus of elasticity, splitting tensile strength, and abrasion resistance) and field observations on full-scale slabs made with each of the studied mixes. All mechanical properties yielded adequate results for concrete for rigid pavements. The metallic fibers increased the strength and elastic stiffness by 7–10%, while the addition of synthetic fibers slowed the development of these properties over time. On the other hand, all the mixes allowed for a successful implementation of full-scale slabs, with none of them showing excessive deterioration after five years of exposure to the outdoor environment. Only minor cracking and some chips in the surface-treatment layer were detected. The strength development of the slabs and their slipperiness were adequate for use in high-speed pavements. The overall analysis of the results shows that concrete made with EAFS can be used in real rigid pavements.

Experimental Study on Friction Characteristics of Micro-Arc Oxidation Modified Layer on Titanium Alloy Surface

In order to study the effect of microarc oxidation modification treatment on the friction properties of titanium alloy surface, the surface treatment layer of Ti-6Al-4V ELI specimen modified by Microarc oxidation surface was sampled, the surface layer hardness, roughness and treatment layer thickness were tested, the microscopic morphology was analyzed, The friction tests of TC4 substrate and micro-arc oxidation treatment surface disc with 25% glass fiber, 15% fiberglass +5% graphite and 60% tin bronze reinforced PTFE pin were carried out, and the results showed that the thickness increased slightly and the surface layer hardness increased by about 75% after the micro-arc oxidation surface modification treatment. Compared with the substrate, the surface roughness is obviously improved, and the friction coefficient of the surface treatment specimen is similar to that of the TC4 titanium alloy substrate, but the wear amount is higher than that of the TC4 titanium alloy substrate.

Mildly hydrophobic biobased mulch: A sustainable approach to controlling bare soil evaporation

AbstractMulching with polyethylene film is the conventional approach to decrease evaporative water loss from agricultural soils, but it is not environmentally sustainable. In this study, a laboratory experiment was conducted to test the potential utility of partially polymerized soybean oil (PSO) coated sands as a surface treatment to reduce bare soil evaporation. Evaporation was tracked for 23.8 d from saturated sand columns treated with a surface layer (1 or 2 cm) of either coated medium sand (MS‐PSO) or coated coarse sand (CS‐PSO). The water drop penetration time (WDPT) was used to assess the hydrophobicity of fresh PSO‐coated sands; the saturated hydraulic conductivity (Ks) and particle density (ρs) were measured as well. The WDPT was also tested on MS‐PSO and CS‐PSO samples aged in four separate environmental conditions for 20–21 d. Both PSO‐coated sands were mildly hydrophobic, and the surface treatment layers reduced evaporative loss by 83–96% over bare soil, which is similar to previous work using extremely hydrophobic chemically treated sands. Freshly coated MS‐PSO had a higher WDPT score and lower Ks than CS‐PSO. After the environmental aging tests, the MS‐PSO and CS‐PSO samples remained mildly hydrophobic. Notably, CS‐PSO had a low initial WDPT (∼1.09 to ∼2.58 s) and a high Ks (2.66 × 10−1 cm s−1), suggesting coarse PSO‐coated sands will permit infiltration. Given these findings, PSO‐coated sand has the potential to be developed into a sustainable alternative to polyethylene film mulch.

Phase-separated polydimethylsiloxane as a dielectric surface treatment layer for organic field effect transistors

We suggest a novel method for treating the surfaces of dielectric layers in organic field effect transistors (OFETs). In this method, a blend of poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) and dimethylsiloxane (DMS) with a curing agent is spin coated onto the surface of a dielectric substrate, silicon oxide (SiO 2), and then thermally cured. X-ray photoelectron spectroscopy, contact angle measurements, and morphology analysis were used to show that the hydrophilic DMS layer is preferentially adsorbed on the SiO 2 substrate during the spin coating process. After thermal curing, the bottom DMS layer becomes a hydrophobic PDMS layer. This bottom PDMS layer becomes thinner during curing due to the upward motion of the hydrophobic PDMS molecules. The FET mobility of the cured system was 10 −2 cm 2/Vs, which is similar to that of polymeric semiconductors on octadecyltrichlorosilane treated SiO 2 dielectric layers. We also discuss the possibility of using this blend method to increase the air-stability of polymeric semiconductors.

Improved adhesion of interconnected TiO2 nanofiber network on conductive substrate and its application in polymer photovoltaic devices

The application of electrospun ceramic nanofibers is limited in electronic devices due to their poor adhesion on conductive substrates. In this regard, a simple method is developed by inserting an ultrathin surface treatment layer between TiO2 nanofiber mats and a conductive substrate to enhance interfacial adhesion. Polymer hybrid photovoltaic devices based on the TiO2 nanofibrous network were fabricated and investigated. Improved device performance was obtained by TiCl4 treatment and interfacial modification for the TiO2 nanofibers, as compared to those without any treatment.

Chloride profiles in surface-treated mortar specimens

Mortar specimens coated with six different surface treatments were immersed in 1 M NaCl solution for almost a year and then chloride profiles were measured. The interfacial chloride content C i between the surface treatment layer and the substrate and the pseudo diffusion coefficient D ps were calculated by fitting the error function solution of Fick’s 2nd law to the profiles in the substrate. All of the surface treatments reduced C i to below the surface chloride content of the untreated control specimen, indicating that chloride diffusion into the substrate was restricted by the surface treatments. The effect of surface treatments on D ps varied. The experimental data are compared with a numerical model of chloride diffusion and discrepancies are discussed in terms of factors not included in the model.

A Quantitative study of polymeric dispersant adsorption onto oxide-coated titania pigments

Polyacrylic acid salts and similar copolymers are used extensively in the coatings industry to disperse oxide-coated titania pigments. The effect of polymer adsorption onto the pigment can vary widely depending on polymer composition, pigment surface treatment, and solution properties such as pH and ionic strength. This investigation examines the effect of molecular weight on the adsorbed layer thickness and stabilizing action of polyacrylic acid dispersants. In order to understand the stabilization mechanism, a DLVO model was used in which the surface treatment layer of the pigment and the adsorbed layer thickness of the dispersant were taken into account. It was found that only this level of detail could account for the degree of stability found in pigment suspensions. Layer thickness and adsorption isotherms indicate that the dispersant molecules do not adsorb completely flat to the pigment surface but with enough loops and tails to provide some electrosteric stabilization.

AC impedance study of sealer- and coating-treated mortar specimens

Chloride diffusion resistance is an important property of surface treatments on concrete in relation to chloride-induced reinforcement corrosion. Currently there is no rapid and accurate method available to measure it. This paper reports on a laboratory investigation of AC impedance measurement as a means of assessing the chloride diffusion resistance of sealers and coatings on mortar. Five surface treatments are studied. It was found that due to the difference in dielectric properties of the surface treatment materials and cementitious mortar, the impedance spectrum of a surface-treated mortar specimen consists of two individual spectra located at high and medium frequencies corresponding to the mortar substrate and the surface treatment layer, respectively. An equivalent circuit for surface-treated mortar/concrete is proposed. Hence the dielectric properties of a surface treatment layer and substrate can be analysed and their individual properties can be studied. The electrical resistance of a surface treatment obtained by impedance analysis was found to correlate well with the chloride diffusion resistance measured by a long-term diffusion cell test. The results suggest that the rapid and non-destructive AC impedance test has great potential in performance monitoring and deterioration mechanism studies of surface treatments.

Development of a surface-treatment method for AIN substrates to improve adhesion with thick-film conductors

A surface-treatment method for AIN substrates to improve adhesion with thick-film conductors has been developed based on the interfacial reaction mechanism between 96% alumina and glasses. The surface-treated AIN substrates were prepared through a combination of oxidation and sol-gel processes. An oxidation atmosphere with high PO2 and low PH2O, which produced the densest Al2O3 layer on AlN, was selected as the oxidation conditions for the surface treatment. A SiO2 layer was deposited on the Al2O3 layer, using the dipping technique with a sol-gel solution. The surface-treated AlN substrates with adequate thicknesses of Al2O3 and SiO2 as the surface-treatment layers showed a good adhesion strength with conventional thick-film conductors. This is the same result as with the 96% alumina substrates, although the adhesion strength of the conductors with bare AlN substrates was poor. These results suggest that glasses in the thick-film conductors react with the surface-treated AlN substrates in the same way as they react with the 96% alumina substrates, and also that the surface-treatment layer consisting of Al2O3 and SiO2 on AlN substrates is effective because it provides good adhesion between such substrates and conventional thick-film conductors.

Utilisation de l’impédancemétrie dans l’industrie de l’emballage

The short term prediction of the long term behavior of packaging systems is one of the main concern of the packaging world. The electrochemical impedance spectroscopy is a powerful tool to achieve such a goal. Corrosion rates of metal and delamination of organic coatings could be evaluated in real media. It is possible to quantify such intrinsic parameters of the organic protection like the thicknesses of varnishes and surface treatment layers, hydration level of natural oxide layer on aluminium thin foils. Examples concerning both steel and aluminium packaging are given.

Ni-Fe-Cr-Mo表面処理層の耐食性

Ni-Fe-Cr-Mo表面処理層の耐食性

垂直二層膜リジッドディスクの構造と特性

Perpendicular magnetic recording is promising for the achievement of higher recording density. Magnetic and crystal orientational properties of double layer rigid disks for perpendicular magnetic recording were studied. Coercive force distribution of the Mo-Cu-permalloy underlayer was investigated as a function of sputtering gas pressure. At optimum Ar gas pressure, good uniformity of coercive force distribution was obtained. Even in double layer medium, crystal orientation of the Co-Cr layer was influenced by the characteristics and thickness of the substrate surface treatment layer. Higher recording density was obtained with lower flying height and a thinner Co-Cr layer. The D50 recording density of 70kFRPI was achieved for a 0.15 μm thick Co-Cr layer and a 0.3 μm thick single pole type head at 0.1 μm flying height.