Adhesion Strength Values Research Articles

FORMATION OF CHROMATED COATINGS ON A PRESS TOOLING IN THE PRODUCTION OF RUBBER PRODUCTS FOR ROCKET AND SPACE TECHNOLOGY

This research analyzes the influence of residual stresses formed as a result of the process of self-propagating high-temperature synthesis on the mechanical properties and durability of structural materials and protective coatings. The main emphasis is placed on the analysis of the relationship between residual stresses and adhesive strength and durability of the obtained coatings. Rubber-based composites may prove to be competitive and eventually replace traditional materials in a number of applications, as there are many advantages to using these materials. For example, rubber-based composites often have a lower density than traditional materials such as metals. This leads to a reduction in the weight of products, which is important in a variety of industries where lightness is a key characteristic. Rubber composites are characterized by cushioning, flexibility, and elasticity, which makes them able to handle dynamic loads and adapt to various forms of deformation without losing structural properties. Research was carried out on parts of press tooling used for manufacturing of rubber-technical products in rocket-space engineering. It was found that residual stresses formed during the SHS process have a significant effect on the adhesion properties of protective coatings. Residual stresses appear after SHS treatment under conditions of thermal self-ignition of SHS charges. At the cooling stage of the SHS process, residual compressive stresses appear as a result of the elastic interaction of the alloyed titanium coating and the structural material, which have different sizes and coefficients of thermal expansion. The maximum values of adhesion strength of titanium coatings on steel 45 were 120-150 MPa when alloyed with aluminum and 180-210 MPa when alloyed with chromium. This research emphasizes the importance of residual stress control for improving the strength and durability of protective coatings obtained under SHS conditions and their possible role in extending the service life of structures and equipment. Additional research in this direction may contribute to process optimization and product quality improvement in the aerospace industry.

Thermophysical and adhesive properties of functional polymer materials based on epoxy resin and silicon-containing component

The work was aimed at developing an adhesive formulation with increased adhesive strength for metals. It contains an epoxy resin of the bisphenol type СHS-TROXY 520 (an analogue of ED-20), an amine hardener triethanolamine (TEA) and a silicon-containing component (3-isocyanatopropyl)triethoxysilane, designated as NCO-Si, with an optimal ratio of components. The content of NCO-Si in the formulations was 0.5, 1.0, 3.0 and 5.0 wt. %, respectively. The gradual transformation of the epoxy system into a three-dimensional network with the formation of ester and urethane groups was shown by IR spectroscopy method. Tensile and shear strength were determined using the tearing machine R-50 in accordance with current standards. It was found that the maximum values of physical and mechanical parameters were obtained when the amount of NCO-Si was 3 wt. %. The maximum values of adhesion strength to steel substrates δst. = 58.5 MPa significantly exceed those for neat epoxy formulations. The shear strength values for steel plates τst. = 21 MPa increase by 60 %, for aluminium plates they are δAl =14.5 MPa and increase by 48 %. The morphology of the samples has been studied by means of optical microscopy. It is shown that the modified NCO-Si samples are characterised by a phase-separated structure. At a minimum amount of NCO-Si (0.5 wt. %), structurally disordered spherical domains with a size of ~1÷3 μm are observed, an increase in the content of the organosilicon component leads to the formation of interconnected regular structures, which are less pronounced at 1.0 wt. % of NCO-Si and clear at 3.0 and 5.0 wt. % of NCO-Si. Thermogravimetric analysis (TGA) was performed as well. It is shown that the modification of epoxy resin by a silicon-containing component with NCO-Si groups leads to an improvement in thermophysical parameters, a decrease in internal stresses and the formation of a material with a structure close to equilibrium.

Shear bond strength between conventional composite resin and alkasite-based restoration used in sandwich technique: An in vitro study.

The success of layered restorations necessitates the utilization of an improved restorative material compatible with composite restorations. Therefore, in this line of research, the strength of adhesion of conventional resin-based dental composite to different filling materials was tested. Conventional composite resin was bonded to four restorative materials (Group I: conventional glass ionomer cement (GIC), Group II: resin-modified glass ionomer cement, Group III: flowable composite, and Group IV: Cention-N) received no surface treatment (Subgroup A: control), sandblasting using 50-µm aluminum oxide particles (Subgroup B), sandblasting and resin adhesive (Subgroup C), acid etch and resin adhesive (Subgroup D), or self-etch resin adhesive (Subgroup E). After 24 h, the strength of adhesion between the conventional composite resin and the other tested filling materials was estimated by using a universal testing machine and compared using one-factor analysis of variance and Tukey's method. The conventional GIC had the minimum values of adhesion strength while the flowable composite and Cention-N had the maximum values of adhesion strength (P < 0.05). The treatment of the used restorative materials with sandblasting and resin adhesive boosted the adhesion strength (P < 0.05). The surface treatment of GIC-based materials with either acid etch and resin bonding agent or self-etch resin bonding agent boosted the adhesion strength (P < 0.05). Cention-N sandblasted and coated with resin adhesive before the application of conventional composite resin in layered restorations is a potential alternative to GIC-based restorations and flowable composite.

Surface treatments of the zirconia-reinforced lithium disilicate ceramic in the adhesion to the resin cement.

This study verified the effect of surface treatments of the zirconia-reinforced lithium disilicate ceramic bonded to resin cement. Ceramic blocks were divided according to treatments (n=10): FA+SRX (Fluoric acid + silane RX), FA+MDP (Fluoric acid + MDP), FA+SCF+MDP (Fluoric acid + silane CF + MDP), FA+MEP (Fluoric acid + MEP), and MEP (Self-etch primer). Resin cement cylinders were made in the ceramic blocks, photoactivated with 1,200 mW/cm² for 40s, stored in water at 37°C for 24h, and evaluated by the microshear strength test, optical failure descriptive analysis (%), surface characterization (SEM) and contact angle (Goniometer). Other samples were submitted to 10,000 thermocycles between 5°C and 55°C. Bond strength data were submitted to two-way ANOVA and Tukey's test. Contact angle to one-way ANOVA and Games-Howell's test (5%). At 24h, MEP showed higher bond strength, and FA+SRX the lower. FA+MDP and FA+SCF+MDP showed similar values and FA+MEP was intermediate. After thermocycling, FA+SCF+MDP, FA+MEP, and MEP showed higher values, and FA+SRX the lower while FA+MDP was intermediate. When the periods were compared, FA+MDP, FA+SCF+MDP, FA+MEP, and MEP showed higher values for 24h while FA+SRX was similar. SEM showed retentive surface and crystal exposure when treated with FA+SCF+MDP. The less retentive surface was obtained with MEP, and the other treatments promoted intermediate irregularities. In conclusion, surface treatment and thermocycling promoted different values of adhesive strength and contact angle in a zirconia-reinforced lithium silicate ceramic. Failures were predominantly adhesive, and the ceramic surface was characterized by different levels of roughness and selective exposure of crystals.

Impact of chemical surface treatment of samples made of domestic zirconium dioxide on adhesive strength

To study the impact of various methods of surface treatment of ZD-based ceramic on adhesive strength. Sandblasting with Al2O3 particles sized 50 μm and application of primers with 10-MDP phosphate monomer were used. Adhesive strength values for following 4 groups of samples were obtained: 1st group - RelyX U200 + sandblasting + Compofix new primer (n=9); 2nd group - Compofix + sandblasting + Compofix new primer (n=9); 3rd group - Panavia F 2.0 + sandblasting (n=9); 4th group (control) - Variolink Esthetic DC + sandblasting + Monobond Plus primer (n=9). The highest strength of adhesion was in the 4th group - 48.71±5.71MPa, the smallest in the 3rd group - 9.49±35.24 MPa. Fully domestic components used in the 2nd group allowed to obtain values of 42.50±9.79 MPa. Adhesive strength in the 1st group was 34.11±4.78 MPa. The absence of the 10-MDP-based primers application in the preparation of ZD ceramic reduces the adhesive strength between resin cement and its surface. The domestic set for fixation of dentures can be effectively used for ZD on the same basis as European analogue.

Optimization of cold spray process parameters to maximize adhesion and deposition efficiency of Ni+Al2O3 coatings

The paper considers the conducted study of the complex effect of low-pressure cold spraying parameters, namely the nozzle inlet temperature, stand-off distance, and powder feed rate on the adhesion and deposition efficiency of coatings from a Ni+Al2O3 powder on VT3-1 titanium alloy substrate. Based on predetermined information, the main levels and intervals of factor variation were selected. The dependence of the adhesion and deposition efficiency on the selected variables was approximated by a second-order polynomial. In accordance with the developed matrix of the experiment (central compositional design), a coating of the studied powder was deposited. The average value of these parameters was determined using standard methods for studying the adhesion strength (ASTM C603) and the deposition efficiency for thermal spray coatings. Based on the results of experimental data, regression equations were obtained for adhesion and deposition efficiency. For the purpose of checking the adequacy of the model, an analysis of variance was performed. It was confirmed that the obtained empirical dependences can be used to predict the adhesion and deposition efficiency of cold spraying of coatings from a Ni+Al2O3 powder on VT3-1 titanium alloy in the specified ranges of values of spraying parameters. Multi-factor optimization of the spraying parameters in order to obtain maximum values of adhesion strength and deposition efficiency was performed using the response surface methodology in the Stat-Ease 360 software. Three-dimensional and contour graphs of the dependence of the adhesion and deposition efficiency on the studied parameters were developed from the obtained empirical models. The optimal combination of parameters of low-pressure cold spraying, which ensures the maximum adhesion (34.78 MPa) and deposition efficiency (29.46%) of the Ni+Al2O3 coating mixture, is the nozzle inlet temperature—537 °C, stand-off distance—11 mm, and powder feed rate—0.6 g s−1.

Evaluation of the shear bond strength of various adhesives on the surface of enamel irradiated with various doses of radiotherapy

We aimed to compare the shear bond strength (SBS) forces on the enamel surface with 2 adhesives after treatment with various radiation doses. A total of 120 premolars were included in the study. The teeth were randomly divided into 5 main groups (n= 24): negative control (without aging), positive control (with aging), 40 Gy, 60 Gy, and 70 Gy radiation. The 40 Gy, 60 Gy, and 70 Gy groups underwent conventional radiotherapy 5 days a week with a dose of 2 Gy each day. After the radiotherapy, all samples except the negative control group were subjected to thermal cycle aging. In all 5 groups, the specimens were divided into 2 subgroups, and half were bonded using 2 adhesives. After bonding, the universal Shimadzu test device was used to analyze the SBS. After the test, the tooth surfaces were examined under a stereomicroscope to determine the adhesive remnant index. When adhesives were compared, Biofix adhesive's bond strength value was statistically higher in the 40 Gy group than in the Transbond XT group (P= 0.001). The SBS value was higher in all irradiated groups than in nonirradiated groups (P= 0.001). When the adhesive remnant index score was analyzed, no significant difference was found among the groups. The SBS increased in irradiated teeth compared with unirradiated teeth, and the SBS values of both adhesives were within the acceptable limits in all radiation groups.

Development of technology for obtaining functional coatings from Kh15Yu5 steel powders

The paper presents the results of research on the development of technology for the application of functional coatings with high values of adhesion strength, microhardness and wear resistance using the method of supersonic cold gas dynamic spraying. Oxidized powder from X15Yu5 steel was used as a starting material for obtaining such coatings.

LVOF sprayed Ti-HAp composite coatings for internal fixation devices in orthopaedic applications

Pure hydroxyapatite, pure titanium, Ti60-HAp (60%Ti), and Ti40-HAp (40%Ti) composite coatings were deposited on 254 SMO steel by Low-Velocity Oxy-fuel (LVOF) spraying. Among the various LVOF sprayed coatings, the Ti40-HAp coating has the highest microhardness and adhesion strength values attributed to its low porosity and low coefficient of thermal expansion. The potentiodynamic polarisation and electrochemical impedance spectroscopy tests also indicated a lower corrosion rate for Ti40-HAp coating in simulated body fluid (SBF). The bacterial adhesion has shown a direct relationship with the surface roughness of the coatings. The bioactivity of the Ti-HAp composite coating was established through an in-vitro bioactivity test. The bioactivity decreased with increasing Ti content in the coating. The formation of rutile TiO2 and CaTiO3 phases significantly enhanced the microhardness, adhesion strength and corrosion resistance.

Adhesion strength and pendulum hardness of some coatings in wood heat-treated by different methods

Beech (Fagus sylvatica L.) and pine (Pinus sylvestris L.) wood specimens were heat-treated separately at three different temperatures (170 °C, 190 °C, and 210 °C) with steam treatment method (STM), oil treatment method (OTM), and hot-air treatment method (HTM). Then, the specimen surfaces were coated with water-based, polyurethane-based, and oil-based varnishes according to industrial applications. The study results show that both hardness and adhesion strength values of STM and HTM treated specimens were similar for both wood species. In contrast, these values were generally lower in OTM-treated specimens. For all applied methods, heat treatment temperature had no significant effect on hardness values. Varnish adhesion strength decreased in all heat-treated wood specimens compared to untreated specimens. Adhesion strength also decreased in STM- and HTM-treated specimens with increasing heat treatment temperature. Hardness values increased in all specimens coated with polyurethane- and water-based varnish compared to the specimens without varnish. However, hardness decreased in the specimens coated with oil-based varnish. In contrast, the highest adhesion resistance was determined in the specimens coated with oil-based varnish under all heat treatment conditions. In addition, the heat treatment method is more effective relative to the hardness values and the treatment temperature is more effective relative to the adhesion strength of varnished pine and beech specimens.

Evaluation of the mechanical properties and corrosion behavior of hBN-Zn composite coatings on the weathering steel

Mechanical tests were conducted and analyzed to investigate the efficacy of Zinc-based coating methods enhanced with hexagonal Boron Nitride (h-BN) nanoparticles. Various methods are employed to deposit these coatings, including Zinc electroplating, Zinc hot-dip, and Zinc-rich coat (ZRC). Different parameters, such as plating time, temperature, voltage, pH, and concentrations of additives, are carefully selected during the process. The introduction of h-BN nanoparticles at varying concentrations into a Zinc- based coating significantly enhanced mechanical properties and performance measures. This improvement was achieved through the diffusion and dispersion of the nanoparticles within the coating. Furthermore, the incorporation of h-BN nanoparticles has exhibited notable enhancements in corrosion resistance when subjected to a 3.5% (NaCl) solution. The best microhardness and adhesion strength values can be achieved by increasing the h-BN concentration (1.5 to 2.5) wt.% in the plating baths. For instance, electroplating with h-BN at a concentration of 15.75 g/l yields a microhardness of 606.7 HV and an adhesion strength of 14.48 MPa. Similarly, hot dip galvanizing with h-BN at a concentration of 2.0% results in a microhardness of 542.1 HV and an adhesion strength of 10.28 MPa. Lastly, when using h-BN at a concentration of 2.5% in ZRC, the microhardness and adhesion strength values obtained are 557.8 HV and 8.5 MPa, respectively. The incorporation of h-BN nanoparticles resulted in a significant improvement and augmentation of the thickness of the coating exhibited the least amount of porosity and the most uniform dispersion when compared to other Zinc composite coatings, namely Zinc electroplating (with a thickness of 97 µm of h-BN at a concentration of 21 g/l), Zinc hot dip (with a thickness of 144 µm of h-BN at a concentration of 2.5%), and ZRC (with a thickness of 123 µm of h-BN at a concentration of 2.5%). Moreover, the utilization of Tafel extrapolation curves and corrosion analysis has demonstrated that Zinc- based coating techniques, when reinforced with the incorporation of h-BN, exhibit significantly improved corrosion current densities (icorr) and corrosion rates (CR). Zinc electroplating technique with h-BN at a concentration of 15.75 g/l yields current density and corrosion rate values of 0.72 µA/cm2 and 0.00659 mpy, respectively. Similarly, Zinc hot dip with a 2.0% h-BN concentration results in current density and corrosion rate values of 3.5 µA/cm2 and 0.032 mpy, while ZRC with a 2.5% h-BN concentration exhibits values of 5.2 µA/cm2 and 0.04758 mpy. OM, SEM, XRD, and EDS mapping analysis were used to characterize the Zinc composite coating's grain structure, grain size, nanoparticle distribution, and chemical composition. The coating matrix contained Zinc and h-BN nanoparticles without impurities. h- BN in the composite coating does not affect grain size. As nucleation sites, h-BN nanoparticles can reduce porosity and refine grains after integration. SubjectsMaterials Chemistry; Corrosion-Materials Science; Surface Engineering-Materials Science.

A Study of the Field Test Method for the Adhesive Performance Evaluation of Self-Adhesive Waterproofing Sheets

In the field of waterproofing concrete structures, the use of self-adhesive waterproofing sheets has become a popular technique for ensuring long-term waterproofing performance. One important characteristic of such sheet materials is maintaining their stable adhesion strength over an extended period. Adhesion testing serves as a crucial method for assessing the long-term adhesion performance. However, a standardized test method, including equipment and criteria, for directly measuring the adhesion strength of waterproofing sheets applied to onsite concrete walls has not yet been established. Therefore, reliance on laboratory evaluation results has been the only option thus far. In this study, a field-applicable adhesion measurement device was developed in an effort to provide a quality control method for self-adhesive waterproofing sheets and to demonstrate the validity of a standardized evaluation method utilizing this device. The developed adhesion measurement device was designed based on the principle of the peel-out test in compliance with the requirements outlined KS F 4934, where the test specimen backing plate can slide into a 1:1 ratio at the same distance as the rise of the tension jig when the tension jig is raised at a 45° angle. By utilizing this device, the adhesion strength values of self-adhesive waterproofing materials applied in the field were compared with those obtained using a laboratory universal testing machine (Salem, MA, USA) (UTM) on the test specimens. Comparative analysis yielded that the standard deviation of the results varied for the tested waterproofing materials, and the overall standard deviation for the UTM measurements was 0.17, while it was 0.18 for the portable field measurement equipment. The results of the comparison indicated that when limited to the scope of the KS measurement method specifications, the possibility for a wider scope of usage can be made possible with more data and studies.

Effects of interface microstructure on adhesion of polyetheretherketone metallized by titanium cold spray

Titanium powders were cold sprayed onto polyetheretherketone (PEEK) to investigate the effects of interface microstructure on bonding. Process guidelines to achieve adherent metallic deposits via cold spray onto thermoplastics are scarce, and mechanisms for metal adhesion onto thermoplastic substrates are unclear. The formation of a transition layer where deposition changes from metal-on-polymer to metal-on-metal deposition can promote adhesion but requires a clearer understanding. The microstructural features of such transition layers provide insights into mechanisms that promote coating adhesion. Select features, including developed interfacial area ratio and gradation of thermal residual stress, correlated to adhesive strength values. The understanding of interlocking mesoscale features formed during cold spray informs the parameter selection for depositing metals onto thermoplastics with strong adhesion.

A study of the thermal properties of alumina/glycidoxy propyl POSS/epoxy adhesives

The nanoparticles of glycidoxy propyl POSS (GPOSS) and alumina microparticles were added into a two-part epoxy adhesive. The filler dispersion in adhesive samples were characterized by EDXA and SEM micrographs indicating weaker dispersion for the highly loaded alumina and/or GPOSS filled compositions. Comparing with neat epoxy resin, DSC thermograms revealed lower heat of cure and higher onset cure temperatures in all compositions. The highest glass transition temperature (Tg) was obtained for the composition containing 10 wt% alumina microparticles and 20 wt% GPOSS, which was about 44 °C higher than that of the neat epoxy. The thermal stability of this composition was improved up to 7 °C based on the first decomposition peak temperature in a TGA test. However, the highest char yield obtained from the TGA test was recorded for a composition containing 20 wt% alumina microparticles and 10 wt% GPOSS. Adhesive lap shear strength values showed a maximum of 13.2 MPa (>40% than epoxy) for the composition containing 10 wt% alumina microparticles and 10 wt% GPOSS. The improvement in adhesive thermal stability was further verified by the results of adhesive strength retention after heat aging at 200 °C for 24 h. It can be concluded that the simultaneous incorporation of GPOSS and alumina in an epoxy results in noticeable improvements in Tg, thermal stability and adhesion strength, mainly due to improved interfacial interactions between GPOSS and alumina particles.

Atomistic investigation on adhesive strength of coupling agents to aluminum

For the adhesion of aluminum, which is of great importance in multimaterialisation, this paper focused on silane coupling agents as one of dominant factors. Amino, mercapto and EP silanes were employed as typical examples, then the atomistic adhesion mechanism was clarified through first-principles calculations and verified in continuum mechanics by tensile tests and finite element analysis. First-principles calculations revealed that the interfacial adhesive strength is governed by stiffness and occurrence of necking, even in atomistic stress-strain relationships. It was also found that stiffness correlates with the deformation mode of the molecular structure, and that necking occurs between the weakest bonds with small bond population and are determined by the interatomic local strain. Interfacial debonding occurred in both first-principles calculations and tensile tests, and the first-principles calculated values of interfacial adhesive strength were in qualitative agreement with the interfacial maximum stress values obtained by finite element analysis based on the breaking load during tensile tests of butt-bonded round bar specimens. Based on these results, this paper summarized effectiveness, applicable conditions and challenges of upscaling method from quantum mechanics to continuum mechanics.

PROPERTIES OF THE COMBINED COATING FOR THE RESTORATION OF WORN CYLINDER LINERS

The service life of the cylinder liner of an internal combustion engine after repair caused by wear of the internal working surface has a shorter service life than a new one. This circumstance necessitates the search for a method of applying a more wear-resistant coating. The possibility of using a combined coating to restore worn cylinder liners by applying a layer of aluminum alloy by cold gas-dynamic spraying followed by micro-arc oxidation of the working surface was investigated. (Research purpose) The research purpose is increasing the life of cylinder liners by applying a combined coating using cold gas-dynamic spraying and micro-arc oxidation of the inner working surface of the cylinders. (Materials and methods) Conducted studies on the adhesive and cohesive strength of the coating and comparative tribological tests to determine the suitability of the coating under study for the repair of cylinder liners. We performed studies according to the standards of OST 90148-74 and GOST 23.224-86, respectively. (Results and discussion) The values of adhesive and cohesive strength were determined for various modes of coating with cold gas-dynamic spraying on a cast-iron base. The optimal loading parameters for accelerated wear resistance tests were identified and the run-in rate, the factor and the wear intensity for the studied and reference coatings were calculated. It was established that the adhesive and cohesive strength is sufficient for the application of this method in practice, the wear resistance of the coated sample exceeds the wear resistance of the reference sample. (Conclusions) The combined coating has sufficient strength indicators and high wear resistance indicators compared to the standard, which makes their use in cylinder liners possible and appropriate, however, further investigation of the coating properties is necessary.

Determination of coating adhesion strength from mechanical mixture of powders deposited by plasma spraying method on die steel Kh12MF

This article presents the results of determining the adhesion strength of a composite coating with Kh12MF steel substrate deposited by plasma spraying method using a domestic installation UPU-3D. As a composite powder, a mechanical mixture of powders PR-NX17SR4 and tungsten carbide clad with nickel in various percentages is used. The sprayed samples are subjected to heat treatment at a temperature of 1025 °C. The adhesion strength is determined by the adhesive method according to GOST 9.304—87. It is found that the highest value of adhesion strength is achieved when using a powder containing equal parts of PR-NX17SR4 and clad tungsten carbide in its composition. It has been also found that heat treatment significantly of the powder to the substrate.

Post-modification of ultra-low molar ratio urea-formaldehyde adhesive with different types and levels of organic acid hardener

Ultra-low (UL) molar ratio urea–formaldehyde (UF) adhesive is a class of UL formaldehyde-emitting adhesive systems for wood-based panels. However, the UL molar ratio exhibits poor reactivity, low cohesion strength, and inferior adhesion. This study aimed to enhance the performance of UL molar ratio UF adhesive via post-modification with the addition of different types and levels of organic acid hardener, such as acetic acid (AA), maleic acid (MA) and citric acid (CA) at 3 and 5% level based on the theoretical solids content of UF adhesive. The solids content, gelation time, viscosity, pH, and free-formaldehyde content decreased with the addition of a higher level of organic acids. This showed that the incorporation of organic acid enhanced the reactivity of the UL molar ratio UF adhesive via cross-linking of carboxylic acid groups and methylol groups or the free-formaldehyde as confirmed by the results of gelation time, pH, and free-formaldehyde content. Post-modification with 5% CA resulted in the lowest solids content, gelation time, viscosity, pH, and free-formaldehyde content. The adhesion strength values of plywood bonded with modified UF adhesive were greater than that of control UF adhesive. In addition, the FE of plywood bonded with modified UF adhesive was lower than that of control UF adhesive. This study showed that 5% CA could be added as a hardener of UF adhesive.

STRENGTH PROPERTIES OF ELASTIC DENTAL MATERIALS ON THE BASE OF MODIFIED POLYACRYLATES

A comparative analysis of the strength properties of hydrogel composition and implants made of polymethylmethacrylate was conducted. Based on polyvinylpyrrolidone and 2- hydroxyethyl-methacrylate including additives of hydrophobic monomers a composition for making soft lining have been proposed. The adhesion strength (tension) of elastic materials bond by the method of “shear” and “breakaway” was studied. It was determined that adhesive strength values of hydrogel composition are quite high. It makes possible applying the composition as cover layer for the removable dentures basis.

Using thermal spray coating method to produce system composites (Ni-Al2O3-B4C(

Thermal plasma spraying method was used for coating the pre-prepared surfaces of turbine blades. Nickel (Ni) was used as a base material with a fixed percentage of alumina (5%Al2O3), and (5,10,15,20,25%) of Boron carbide (B4C) as reinforcement material. Cermet powders were mixed for one hour, then the coating bases of steel type (316L) were prepared and roughened using sandblasting to increase the adhesion strength between the coated materials and the base. The bonding material represented by (Ni-22% Cr-10%Al-1%Y) was sprayed with a thickness of (150µm), and then the base and reinforcement material were sprayed with a thickness of (350-400 µm). Thus, the final thickness of the prepared samples was (550-500 µm). After that, the samples were sintered at 900°C for two hours. The hardness test was applied to the samples, indicating the best hardness after sintering at (25%) reinforcement ratio of 590Hv. As for porosity, its lowest value was obtained at 7%, while the best value of adhesion strength was obtained after sintering at (25%) of B4C. However, the results of the scanning electron microscope (SEM) showed the weakness and the presence of pores in the coating layers at the low percentage of reinforcement. While the mechanical and physical properties were improved with the increase in the percentage of reinforcement to reach the best at 25% of B4C.