Influence of Curing Condition on the Adhesive Strength of EVA Modified Mortar to Tile

The reducing water effectiveness of EVA latex and powder was observed. Adhesive strength of EVA modified mortar to tile under different curing condition was studied. And the adhesive strengths of mortars modified by EVA latex and by EVA powder were compared. The results show that the reducing water effectiveness is improved by 36.12% and 21.55%, respectively, when the content of EVA latex and powder are 8% and 4%. EVA latex and powder can improve the adhesive strength of modified mortar to tile under the standard curing, high temperature curing, and freeze-thaw circle curing. EVA latex can improve the water resistance obviously, besides improve the adhesive strengths of standard curing and high temperature curing, comparing with EVA powder.

Microstructures and Adhesive Strength of Three Kinds of Ceramic Coatings

In gas turbine engine, the study of ceramic thermal resistance coating has always been paid more attention because it can effectively reduce metal interface temperatures, improve corrosion and/or oxidation resistance and extend life. The microstructures, SEM microfractographs and adhesive strength of three kinds of zirconia plasma-sprayed ceramic coating were investigated. The results indicated that nanostructured zirconia coating have higher adhesive strength and better micro-cracking resistance properties compared with magnesia or yttria stabilized zirconia coating because its less quantities laminar internal structures and closed packed structures with less quantities and uniform distribution cavities. The sprayed power is also an important factor affecting adhesive strength of nanostructured zirconia coating.

TENSILE AND ADHESIVE STRENGTHS OF FINE TiN FILM ON Ti SUBSTRATE

The cantilever bending test,particularly monitored by an acoustic emission technique, was adopted to measure the tensile and interfacial adhesive strengths of the HCD ion plated fine TiN film on pure Ti substrate.The behaviors of film damaging were found to be characterized by:an internal tensile stress which exceeded its tensile strength for TiN facing upward,and a shearing stress along film substrate interface which exceeded its adhesive strength for TiN facing downward.The measured tensile and adhcsive strengths are 603 and 242 MPa respectively.

Adhesive strength of CVD diamond thin films quantitatively measured by means of the bulge and blister test

Large advancement has been made in understanding the nucleation and growth of chemical vapor deposition （CVD） diamond, but the adhesion of CVD diamond to substrates is poor and there is no good method for quantitative evaluation of the adhesive strength. The blister test is a potentially powerful tool for characterizing the mechanical properties of diamond films. In this test, pressure was applied on a thin membrane and the out-of-plane deflection of the membrane center was measured. The Young＇s modulus, residual stress, and adhesive strength were simultaneously determined using the load-deflection behavior of a membrane. The free-standing window sample of diamond thin films was fabricated by means of photolithography and anisotropic wet etching. The research indicates that the adhesive strength of diamond thin films is 4.28±0.37 J/m^2. This method uses a simple apparatus, and the fabrication of samples is very easy.

The Study of the Grit-blasting Parameters and Their Effects on the Adhesive Strength of the Plasma Sprayed Coatings

Surface Preparation is very important in adhesive b on ding of spray coatings to the surface of a work piece. The common practice is gr it-blasting of the surface before subjecting it to the spray coating process. In this study, grit-blasting of an AISI 4130 steel (of different heat treatmen ts) with Al 2O 3 particles was studied. Various grit-blasting parameters such as blasting particle size, the distance between blasting nozzle and the work pi ece (25, 30 and 40 cm.), blasting pressure (3,4,5,6 and 7 bars), blasting time ( 3, 6 and 10 seconds), and the blasting angle (45° and 90°) were examined in or der to find the optimum roughness. The mean roughness (Ra) of the grit-blasted surfaces were measured and the vari ations of the roughness with respect to the above mentioned variables were studi ed. The results show that by increasing blasting time, surface roughness increas es up to a maximum and then slightly decreases it with further duration of t he process. On the other hand a lengthy blasting causes some undesirable results such as an increase in residual particles between surface irregularities. There fore an optimum blasting time is of great importance. Increasing the blasting pr essure also provides a rougher surface, but in grit blasting of harder specimens the surface roughness decreases when the pressure reaches a certain limit. About the blasting angle, it was noticed that an angle of 45° results in less r esidual particles between the surface irregularities, in comparison to the angle of 90°. After grit-blasting, the specimens were plasma spray coated with 80% ZrO 2-20 % Y 2O 3 powder. The adhesive strength of the coating to the substrate was the n measured according to the DIN 50160 standard. The results show that for a certain base metal, the adhesive strength is directl y related to the surface roughness of the base material. Residual particles afte r grit-blasting the surface of the specimens can also have a strong deteriorati ng effect on adhesive strength. Finally, it was shown that the hardness of the b ase material had a direct effect on the adhesive strength of the sprayed coating s.

Design of an Experimental Set‑up Concerning Interfacial Stress to Promote Measurement Accuracy of Adhesive Shear Strength Between Ice and Substrate

Accumulation of ice on airfoils and engines seriously endangers the safety of the fight.The accurate measurement of adhesion strength at the ice-substrate interface plays a vital role in the design of anti/de-icing systems.In this pursuit,the present study envisages the evaluation of the stress at the icesubstrate interface to guide the design of experimental set-ups and improve the measurement accuracy of shear strength using the finite element analysis(FEA)method.By considering such factors as the peeling stress,maximum von-mises stress and uniformity of stress,the height and radius of ice and the loading height are investigated.Based on the simulation results,appropriate parameters are selected for the experimental validation.Simulation results show that the peeling stress is decreased by reducing the loading height and increasing the height of ice.Higher ice,increasing loading height and smaller ice radius are found to be beneficial for the uniformity of stress.To avoid cracks or ice-breaking,it is imperative that the ice should be of a small radius and greater height.Parameters including the ice height of 25 mm,radius of 20 mm,and loading height of 9 mm are adopted in the experiment.The results of FEA and the experimental validation can significantly enhance the measurement accuracy of shear strength.

Adhesion strength of tetrahydrofuran hydrates is dictated by substrate stiffness

Understanding the hydrate adhesion is important to tackling hydrate accretion in petro-pipelines.Herein,the relationship between the Tetrahydrofuran(THF)hydrate adhesion strength(AS)and surface stiffness on elastic coatings is systemically examined by experimental shear force measurements and theoretical methods.The mechanical factor-elastic modulus of the coatings greatly dictates the hydrate AS,which is explained by the adhesion mechanics theory,beyond the usual factors such as wettability and structural roughness.Moreover,the hydrate AS increases with reducing the thickness of the elastic coatings,resulted from the decrease of the apparent surface elastic modulus.The effect of critical thickness for the elastic materials with variable elastic modulus on the hydrate AS is also revealed.This study provides deep perspectives on the regulation of the hydrate AS by the elastic modulus of elastic materials,which is of significance to design anti-hydrate surfaces for mitigation of hydrate accretion in petro-pipelines.

Adhesion of Technical Lignin-Based Non-Isocyanate Polyurethane Adhesives for Wood Bonding

Lignin is the most abundant aromatic natural polymer,and receiving great attention in replacing various petro-leum-based polymers.The aim of this study is to investigate the feasibility of technical lignin as a polyol for the synthesis of non-isocyanate polyurethane(NIPU)adhesives to substitute current polyurethane(PU)adhesives that have been synthesized with toxic isocyanate and polyols.Crude hardwood kraft lignin(C-HKL)was extracted from black liquor from a pulp mill followed by acetone fractionation to obtain acetone soluble-HKL(AS-HKL).Then,C-HKL,AS-HKL,and softwood sodium lignosulfonate(LS)were used for the synthesis of technical lignin-based NIPU adhesives through carbonation and polyamination and silane as a cross-linker.Their adhesion per-formance was determined for plywood.FTIR spectra showed the formation of urethane bonds and the reaction between lignin and silane.The NIPU adhesives prepared with C-HKL showed the highest adhesion strength among the three lignin-based NIPU adhesives.As the silane addition level increased,the adhesion strength of NIPU adhesives increased whereas formaldehyde emission decreased for all NIPU adhesives prepared.These results indicate that NIPU adhesives based on technical kraft lignin have a great potential as polyol for the synth-esis of bio-based NIPU adhesives for wood bonding.

Study on ASTM Shear-loaded Adhesive Lap Joints

Finite element analyses and experiments are conducted to analyze the mechanical behavior of ASTM shear-loaded adhesive lap joints. Adhesive is characterized for the stress-strain relation by comparing the apparent shear-strain relations obtained from finite element analysis and experiments following ASTM D 5656 Standard. With the established stress-strain relation, two failure criteria using equivalent plastic strain and J-integral are adopted to predict the failure loads for joint specimens following ASTM D 5656 and ASTM D 3165 Standard, respectively. Good correlation is found between the finite element results and the experimental results. The strength of ASTM D 3165 specimens with debonding defects is also studied. Calculation results shows that experiment data following the standards provide only relative material constants, such as apparent shear modulus and strengths. Further investigation is required to find out the engineering properties needed for actual joint design. For the specimens with debonding defects, the locations of defects have great effects on their load bearing ability.

Evaluation for Adhesion Strength of Coating and Substrateby Burying Beforehand Specimen

Adhesion strength is an important target in evaluating the quality of coating layers.The traditional way of adhesion strength test is bonding pull off method for thick layers and scratch test for thin films.The drawbacks of these two methods are discussed in this paper,and an evaluating method for adhesion strength of coating by burying beforehand specimen is proposed.The adhesion strength of samples is measured with two methods.The dispersity of testing data is lower than that in the ASTM C663 79 Standard.

ADHESION STRENGTH OF COATING SUBSTRATE AND SURFACE MORPHOLOGY OF PRETREATMENT

Premature failure of coated tool often results from a poor adhesion of coating-substrate and shortens the lifetime of the tool. The results of increasing the adhesion strength of thin film coatings on cutting tool inserts by pretreating the inserts with sandblasting technique to obtain a desirable surface morphology of the inserts are presented. A geometric model representing the ideal surface morphology is established to enhance the nucleation density and adhesion strength of coating-substrate. Thin film coating experiment is conducted on the substrates of four different sample groups. Indentation and wear tests are performed on coated inserts to evaluate the effect of sandblasting on the adhesion strength of the coatings. A theoretical analysis is provided on the formation and growth of atom clusters in terms of the contact angle and the thermodynamic barrier of a substrate to predict thin film nucleation.

EFFECT OF ARTIFICIAL WEATHERING AND TEMPERATURE CYCLING ON THE ADHESION STRENGTH OF WATERBORNE ACRYLATE COATING SYSTEMS USED FOR WOODEN WINDOWS

The adhesion of coatings to wood is important for their long-term performance.In this study,the adhesion strength of water-based acrylate coatings used for wooden windows after exposure to artificial weathering(AW)and temperature cycling(TC)was investigated.The analysis of the adhesion quality of coatings was performed via a pull-off test and failure characteristics.The 3-layered and 4-layered white and brown acrylate dispersions from six different producers were compared and the effect of coating thickness on adhesion strength was investigated.The adhesion strength values proved to be very variable.After AW,the adhesion strength and its variability increased for all the samples.TC had no statistically significant effect on the adhesion strength values.White coating systems were initially characterized by lower adhesion strength,but after AW and TC,they reached higher adhesion strength values than brown ones.The overall highest adhesion after AW and TC was recorded for the coatings based on alkyd-acrylate hybrid basis(Producer 3),while the lowest adhesion variability after AW was measured for one type of tested acrylate coating(Producer 4).The effect of different layering on adhesion strength was not demonstrated in this study.

New insights into the deposition of natural gas hydrate on pipeline surfaces:A molecular dynamics simulation study

Natural gas hydrate(NGH)can cause pipeline blockages during the transportation of oil and gas under high pressures and low temperatures.Reducing hydrate adhesion on pipelines is viewed as an efficient way to prevent NGH blockages.Previous studies suggested the water film can greatly increase hydrate adhesion in gas-dominant system.Herein,by performing the molecular dynamics simulations,we find in water-dominant system,the water film plays different roles in hydrate deposition on Fe and its corrosion surfaces.Specifically,due to the strong affinity of water on Fe surface,the deposited hydrate cannot convert the adsorbed water into hydrate,thus,a water film exists.As water affinities decrease(Fe>Fe_(2)O_(3)>FeO>Fe_(3)O_(4)),adsorbed water would convert to amorphous hydrate on Fe_(2)O_(3)and form the ordered hydrate on FeO and Fe_(3)O_(4)after hydrate deposition.While absorbed water film converts to amorphous or to hydrate,the adhesion strength of hydrate continuously increases(Fe<Fe_(2)O_(3)<FeO<Fe_(3)O_(4)).This is because the detachment of deposited hydrate prefers to occur at soft region of liquid layer,the process of which becomes harder as liquid layer vanishes.As a result,contrary to gas-dominant system,the water film plays the weakening roles on hydrate adhesion in water-dominant system.Overall,our results can help to better understand the hydrate deposition mechanisms on Fe and its corrosion surfaces and suggest hydrate deposition can be adjusted by changing water affinities on pipeline surfaces.

Quantitative lithium substitution of carboxyl hydrogens in polyacrylic acid binder enables robust SiO electrodes with durable lithium storage stability

The design of advanced binders plays a critical role in stabilizing the cycling performance of large-volume-effect silicon monoxide(SiO)anodes.For the classic polyacrylic acid(PAA)binder,the self-association of-COOH groups in PAA leads to the formation of intramolecular and intermolecular hydrogen bonds,greatly weakening the bonding force of the binder to SiO surface.However,strengthening the binder-material interaction from the perspective of binder molecular regulation poses a significant challenge.Herein,a modified PAA-Li_(x)(0.25≤x≤1)binder with prominent mechanical properties and adhesion strength is specifically synthesized for SiO anodes by quantitatively substituting the carboxylic hydrogen with lithium.The appropriate lithium substitution(x=0.25)not only effectively increases the number of hydrogen bonds between the PAA binder and SiO surface owing to charge repulsion effect between ions,but also guarantees moderate entanglement between PAA-Li_x molecular chains through the ion-dipole interaction.As such,the PAA-Li_(0.25)/SiO electrode exhibits exceptional mechanical properties and the lowest volume change,as well as the optimum cycling(1237.3 mA h g^(-1)after 100cycles at 0.1 C)and rate performance(1000.6 mA h g^(-1)at 1 C),significantly outperforming the electrode using pristine PAA binder.This work paves the way for quantitative regulation of binders at the molecular level.

Effect of 10% Si addition on cathodic arc evaporated TiAlSiN coatings

The effect of 10% Si （mole fraction） addition on TiAlSiN coatings was studied. Ti0.5Al0.5N, Ti0.5Al0.4Si0.1N and Ti0.55Al0.35Si0.1N coatings were deposited on WC？Co substrates by cathodic arc evaporation. The microstructure and mechanical properties were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, scanning electron microscopy （SEM）, nano-indentation measurement and scratch test. The mechanisms of how Si affects the properties and failure modes of TiAlSiN coatings were also discussed. The results show that the addition of 10% Si results in the formation of nc-（Ti,Al,Si）N/a-Si3N4 nano-composite structure. The hardness and toughness of TiAlSiN coatings increase, whereas the coating adhesion strength decreases. Compared with Ti0.55Al0.35Si0.1N coating, Ti0.5Al0.4Si0.1N coating has higher hardness but lower toughness. The dominant failure mode of TiAlN coating is wedging spallation due to low toughness and strong interfacial adhesion. The dominant failure mode of TiAlSiN coatings is buckling spallation due to improved toughness and weakened interfacial adhesion.

Properties of W/DLC/W-S-C composite films fabricated by magnetron sputtering

A kind of W/DLC/W-S-C composite film was fabricated by magnetron sputtering method.Effects of WSx content on the structure and the adhesion of the composite films were investigated.In addition,tribological behavior of the composite films was studied in the conditions of the ambient air and N2 gas atmosphere by ball-on-disk tester.The results indicate that the composite films show dense and amorphous microstructure.The WCx and WSx compounds are found in amorphous diamond like carbon matrix in the top layers of W-S-C.A proper WSx content is beneficial for improving the adhesion of the composite films.In air atmosphere,the composite films with high C content have better wear resistance and the friction coefficients range from 0.15 to 0.25.In N2 condition,high WSx content is benefit for the wear resistance and the friction coefficients of the composite films range from 0.03 to 0.1.

Weatherability Studies on External Insulation Thermal System of Expanded Polystyrene Board,Polystyrene Granule and Polyurethane Foam

Atmospheric exposure tests including two experimental stages of high temperature-spraying water cycle and heating-refrigeration cycle were carried out on three currently used ETIS of expanded polystyrene（EPS） board,polystyrene granule mortar and polyurethane foam in order to study the weatherablility of external thermal insulation system（ETIS）.The change rules of adhesive strength were hereby studied at different time period of atmospheric exposure tests.The experimental results show that the adhesive strength of three kinds of ETIS changes a little during high temperature-spraying water cycle,but the adhesive strength of ETIS with EPS board decreases significantly after heating-refrigeration cycle.The lowering rate of adhesive strength with painting finishes is obviously faster than that of tile finishes for ETIS of EPS board during heating-refrigeration cycle.The weatherability of ETIS with EPS board is worse than the other two,and ETIS of polystyrene granule mortar and polyurethane foam are more suitable than ETIS of EPS board in cold area.

Fabrication and Application of High Quality Diamond-coated Tools

Diamond-coated tools were fabricated using Co-cemented carbide inserts as substrates by the electronically aided hot filament chemical vapor deposition (EACVD). An amount of additive in an acid solution was used to promote the Co etching of the substrate surface. The surface of the WC-Co substrate was decarburized by microwave plasma with Ar-H 2 gas. Effect of the new substrate pretreatment on the adhesion of diamond films was investigated. A boron-doped solution was brushed on the tool surface to diffuse boron into the substrates during diamond deposition. A new process was used to lower the surface roughness of diamond thin films by appropriately controlling deposition parameters. It consists of a composite diamond film chemical vapor deposition procedure including first the deposition of the rough polycrystalline diamond and then the fine-grained diamond. The research results show that the pretreatment including both Co etching in acid solution and Ar-H 2 etching decarburization by microwave plasma is an effective method to enhance adhesive strength. An adequate amount of boron dopant solution can effectively suppress the cobalt diffusion to the surface and avoid the catalytic effect of Co at the high temperature. The composite film CVD process can deposit smooth diamond films with low surface roughness. It is of great significance for improvement of the cutting performances of diamond-coated tools using the above new technology to deposit diamond coatings with the low surface roughness and high adhesive strength on WC-Co substrates.

Effect of initial deposition behavior on properties of electroless Ni-P coating on ZK60 and ME20 magnesium alloys

The composition of magnesium alloys is greatly associated with initial deposition behavior of electroless Ni-P coatings.Thus,the initial deposition behavior of electroless Ni–P coatings on ZK60 and ME20 alloys was investigated.The results indicated that differences in the alloy compositions significantly influenced the initial deposition process and the adhesive strength,corrosion resistance,and crystal structure.The initial deposition of coatings on ZK60 and ME20 alloys preferentially occurred on the precipitates.The precipitates in ZK60 alloy had higher chemical activity after HF activation and controlled the initial deposition rate of the coating.The initial deposition rate of the coating on ME20 alloy mainly depended on the density of the Mg F2 film formed by HF activation rather than on the precipitates.Owing to differences in the initial deposition process,the coating on ZK60 alloy had higher adhesive strength and better corrosion resistance than that on ME20 alloy.The coatings on ZK60 and ME20 alloys mainly had crystalline structures,and the coating on ME20 alloy had also a slight microcrystalline structure.

Effect of ball peening of substrate on microstructure, phase evolution and properties of electrophoretically deposited YSZ/(Ni,Al) composite coatings

YSZ/（Ni, Al） composite coatings were deposited on Inconel600 superalloy with ball peening （BP） and without （non BP）treatment using the electrophoretic deposition （EPD） technique, followed by vacuum sintering method. The structures and phaseevolution of the coatings were studied with X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersivespectrometry （EDS）. The relation between microstructures and properties of the BPs-coated samples was discussed. The results showthat the adhesion strength and gain mass of the BPs-coated samples with isothermal oxidation at 1100℃ for 100 h are 3.3 N and0.00817 mg/cm^2, respectively, while those of the non-BPs-coated sample are 2.6 N and 0.00559 mg/cm^2, respectively. The EDSmapping analysis indicates that an obvious outward diffusion of Cr from the substrate to BPs coated samples occurs after isothermaloxidation. The BPs-coated sample shows the superior adhesion and oxidation resistance compared with non-BPs-coated samples.