Papers by Keyword: Adhesion Strength

Abstract: Alumina (Al₂O₃) is a technical ceramic widely selected for demanding applications due to its excellent material properties, such as high strength, corrosion resistance, and thermal stability. In this study, the effect of the sintering temperature of 3D-printed alumina to its surface characteristics and its subsequent performance as a copper-metallized ceramic substrate was investigated. Green parts of alumina samples were prepared using stereolithography (SLA) 3D printing, debound, then sintered at temperatures ranging from 1660°C to 1740°C. Surface roughness was quantified using Atomic Force Microscopy (AFM), while the copper layer's adhesion was assessed via tape and burnishing tests. Electrical conductivity was measured with a four-point probe. A non-monotonic relationship between sintering temperature and surface roughness was observed. Roughness (Ra​) decreased as temperature increased from 1660°C to 1720°C, attributed to enhanced densification. However, increasing the temperature to 1740°C led to grain coarsening and a slight increase in roughness due to excessive grain growth. Stronger copper adhesion was achieved on smoother surfaces produced at optimized sintering temperatures. Electrical conductivity was also determined with a minimum sheet resistance of 0.089 mΩ/sq achieved.

Abstract: Nickel-based coatings are a vital technology in industrial applications, offering protection to metallic objects against high temperatures, wear, corrosion, and erosion. The current research work examines the deposition of NiCrBSi powder in Stainless steel (AISI SS 304) using the high-velocity oxy-fuel (HVOF) thermal spray coating technique. The effects of HVOF-deposited NiCrBSi coatings on the microstructure, morphology, and mechanical and physical properties of the coated stainless steel. Microstructural and morphological analyses were performed using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD) to characterize the coating. The coatings were systematically assessed for surface roughness, deposition efficiency, coating thickness, and porosity. Adhesion strength was measured using a pull-off adhesion tester to ensure robust bonding. The results demonstrate that HVOF-sprayed NiCrBSi coatings possess low porosity (2-3%), strong adhesion (45–55 MPa), and increased hardness, making them highly suitable for high-temperature, anti-wear applications, with improved durability and performance under harsh operating conditions.

Abstract: This paper presents the results of a study that aimed to analyze the flexural behavior of self-compacting rubberized steel-reinforced concrete. A four-point bending test was performed on three reinforced beams made with conventional concrete and three similar beams made using the same concrete mixture with a 10% volumetric substitution of natural aggregates with rubber particles. The results showed a statistically significant decrease (about 24%) in the cracking load for the rubberized concrete beams, which is attributed to the reduced indirect tensile strength and modulus of the rubberized concrete. However, no statistically significant difference was observed between the control and rubberized concrete beams in terms of ultimate load and maximum deflection Additionally, the estimated adhesion strength, based on the average measured crack spacing, was also statistically similar between the tested beams. Existing equations derived from reinforced concrete beam theory were deemed suitable for rubberized concrete, since the estimation trends for these equations were similar for both types of concrete. Therefore, the main conclusion of this study is that the presence of rubber particles, at a 10% volumetric substitution, did not affect the flexural behavior particularly the quality of adhesion between the reinforcing bars and the surrounding concrete of steel-reinforced beams.

Abstract: To increase cohesiveness, toughness, impermeability, and adhesion strength in cementitious materials like mortars and concrete, vinyl acetate ethylene (VAE) copolymer redispersible powder (RDP) is used. However, due to numerous variety of material, choosing an original performing RDP is challenging. The goal of this study is to assess the bond strength to concrete surfaces of various redispersible polymer-modified cementitious coatings under various accelerated settings. The outcomes showed that the RDP backbone composition has a significant influence on the coatings' adhesion strength. Methyl methacrylate (MMA) and Vinyl chloride (VC) present as comonomers in RDP exhibit outstanding thermal stability and boost tensile adhesion strength by 41% and 21%, respectively, in comparison to other RDPs. According to SEM studies, the VC- RDP stimulates the formation of fibrous ettringite, producing a uniform and cohesive microstructure.

Abstract: In this study, an eco-friendly coconut oil-based polyol blend was synthesized for bio-based waterborne polyurethane (WBPU) and WBPU-silane composite coatings. It was demonstrated that an increase in silane content incorporated into the WBPU matrix significantly enhanced the corrosion protection of WBPU coatings. Results also show a fourfold increase in the adhesion strength of WBPU-silane composite coatings as compared to that of bare WBPU coatings. Further, the water contact angle revealed that hydrophobic properties increase as the silane content incorporated into the WBPU matrix increases. This work provides a novel route for enhanced corrosion protection utilizing a bio-based polyol blend.

Abstract: Fan-out wafer-level package is a very promising packaging technology with good thermal and electrical performance. The fan-out wafer-level package exhibits beneficial features such as low profile, high I/O density, low cost, and efficient computing. The package experiences large temperature variations in the assembly phase which causes internal stresses. In particular, the mismatch between the coefficient of thermal expansion of the epoxy molding compound and the substrate due to the cool down phase of the cure process causes the internal stresses in the package. These internally induced stresses result to interfacial delamination. In this study, the interfacial delamination on a fan-out wafer-level package right after post mold cure of glass wafer was evaluated using the stress-based damage index through the finite element analysis in the ANSYS software package. The model was validated by comparing the simulation result of the glass wafer warpage to the existing experimental result from literature. From the warpage simulation of the glass wafer, the region on the package with high stress level was located and examined which may cause interfacial delamination. The maximum shear stress and principal stress at the epoxy molding compound and the Silicon chip interface was found to exceed the adhesion strength. This indicates that the interfacial delamination is inevitable. The information obtained from the stress analysis of molded wafer provides insight for the possible interfacial failure of fan-out wafer-level package in the individual package when subjected to thermomechanical loads.

Abstract: The influence of electrolysis conditions and the composition of electrolyte for iron plating in the flow of electrolyte on the adhesion strength, microhardness and wear resistance of coatings were studied. The optimal composition of electrolyte for iron plating and the structure of coatings that provide the highest abrasive wear resistance were determined. Advisability of using iron plating in the flow of electrolyte for restoration of spools for hydraulic control valves was demonstrated.

Abstract: Conventionally, short fibers such as steel and synthetic fibers have been mixed into spray mortar used for slope protection to enhance resistance against cracking and durability. However, in the quest of higher performance fiber-reinforced mortar with reduced impact on the environment, natural fibers such as bamboo fibers may play a vital role. Thus, the tensile strength and the bond strength of bamboo fibers used for spray mortar were examined by laboratory tests. The mechanical properties of bamboo-fiber-reinforced spray mortar were examined under cyclic wet and dry conditions along with its resistance against freezing and thawing by a spray test. It was confirmed that 0.75% mixture of bamboo fibers in spray mortar successfully improved mechanical properties and durability. These include adhesion strength to the base surface following exposure to cyclic wet/dry conditions and overall resistance against freezing/thawing. Moreover, higher compressive strength, flexural toughness and adhesion strength to the base surface were achieved by further mixing in vinylon fibers or fly ash in addition to bamboo fibers.

Abstract: The article presents the results of a study of the influence of inertial forces on the adhesion of the coating to the external surface of a body of revolution during thermal spraying. A mathematical apparatus is proposed for calculating the inertia forces, acting on a particle of coating, applied to the outer surface of the bodies of revolution. As a result, dependencies have been revealed that allow predicting the adhesion strength of the coating with the steel base during thermal spraying.

Abstract: The article deals with the strength of adhesion of coatings with the parts of type «shaft». In accordance with the above separation, gas-thermal methods of spraying and thermal power sintering have an adhesive interaction of particles and coatings. The use of thermomechanical treatment of preformed coatings (applied by thermal spraying) makes it possible to increase the adhesion strength of coatings with parts of «shaft» type. For a quantitative assessment of the adhesion strength of coatings with the base metal, a shear coating method was used. An experiment to determine the adhesion strength of samples of steel with various applied coatings is considered. It was concluded that the adhesion strength of the coatings obtained using the hydrogen-propane mixture was slightly superior.