Search Results (79)

Timber–steel hybridisation offers a balanced approach by capitalising on the high strength-to-weight ratio and sustainability of the timber while also benefiting from the high stiffness and ductility of the steel, contributing to the improved performance of hybrid structural elements. This paper reviews key aspects of timber–steel hybridisation, with a particular emphasis on the connection methods between timber and steel, including adhesive bonding and mechanical fastening, as well as the different types of reinforcement configurations. In particular, this review covers two main types of adhesives used in timber–steel hybrid systems, namely, epoxy and polyurethane, and two primary types of mechanical fasteners, namely, bolts and screws. The mechanical performances of all hybridisation methods are reviewed. The importance of surface treatments, such as shot blasting for steel and mechanical abrasion for timber, is also discussed as a key factor in optimising adhesive bonds. Furthermore, various reinforcement configurations, including top, bottom, side, and embedded arrangements, are evaluated for their impact on the structural efficiency and fire performance. To support this evaluation, calculations have been carried out to illustrate how different reinforcement configurations influence the stress distribution in timber–steel hybrid beams. By providing detailed insights into these critical aspects, this paper serves as a valuable decision-making tool, offering guidance for researchers and industry professionals for selecting the appropriate bonding techniques and configurations to meet specific structural objectives and advance sustainable construction practices. Full article

In the manufacturing process of precision micro parts, burrs generated in cutting and grinding processes cause various problems. Shot blasting was used in the deburring technology of cutting and grinding burr in the process of manufacturing hypodermic needles for the human body. However, we found that a secondary burr facing the inside occurs on the chin part of the needle during the blasting process. The existence of burrs on a hypodermic needle also causes several problems. We developed a new deburring method by using a vibration magnetic abrasive machining process. Our experimental results validated the effectiveness of the magnetic deburring method. Full article

Surface roughness refers to the micron- or nanometer-scale irregularities (bumps and grooves) on material surfaces, and it varies greatly as particles are refined, affecting their flotation behavior, wettability, and bubble–particle interactions. In this paper, the main roughening and measurement methods for surface roughness are summarized, the effects of surface roughness on flotation behavior and wettability are reviewed, and the main wettability models for rough surfaces are also introduced. Grinding is the most commonly used method, while other methods, such as acid etching, abrasion, sand-blasting, ultrasonic pretreatments, and microwave treatments, have also been explored. Most research shows that increasing the surface roughness effectively enhances the hydrophobicity of hydrophobic surfaces and the hydrophilicity of hydrophilic surfaces. This improvement leads to better flotation recovery and kinetics for hydrophobic surfaces, whereas it deteriorates that for hydrophilic surfaces. Moreover, the relationship between surface roughness and bubble–particle interactions, including bubble–particle attachment, interaction energy, and interaction force, is introduced. Most research shows that increased surface roughness effectively decreases the attachment time and energy barrier and increases the adhesion force between air bubbles and rough hydrophobic surfaces. Conversely, these effects can be detrimental to rough hydrophilic surfaces. This paper also addresses existing problems and challenges in the field and offers references and suggestions for future research efforts. Full article

This study evaluates the effects of three mechanical pre-treatment methods on S235JRG2 steel sheets: blasting with a synthetic corundum (F40), blasting with steel shot (S170), and grinding with synthetic corundum (P40). Untreated samples served as a reference. The analysis of mechanical pre-treatments focused on surface integrity, including measurements of surface roughness parameters Ra and Rz (ISO 21920-2) and subsurface microhardness (ISO 6507-1). Zinc coatings were assessed through mechanical testing (cupping test, ISO 1520) and corrosion testing in a neutral salt spray environment (ISO 9227), with results evaluated using digital image analysis. Experimental findings indicate that electroplated zinc deposition rates are influenced by surface roughness, while subsurface microhardness has no significant effect. In contrast, for hot-dip galvanizing, both parameters impact the process. The mechanical properties of electroplated zinc coatings are further affected by steel surface integrity, whereas hot-dip zinc coatings are primarily governed by intermetallic phase formation, making the influence of steel surface integrity statistically negligible. Corrosion testing revealed that blasting with a synthetic corundum is particularly unsuitable, as it leads to numerous inhomogeneities in both coating types, accelerating corrosion degradation. Full article

We used high-power impulse magnetron sputtering (HiPIMS) to deposit tungsten carbide films for superior wear protection in abrasive environments. In order to sample different W-to-C ratios more efficiently, a combinatorial approach was chosen. A single sputter target with two equal segments was used, consisting of an upper tungsten and lower graphite segment. This allowed us to vertically sample various elemental compositions in just one deposition run without creating graphitic nano-layers by rotating the substrate holder. The substrate bias voltage, being one of the most effective process parameters in physical vapor deposition (PVD), was applied in both constant and pulsed modes (the latter synchronized to the target pulse). A direct comparison of the different modes has not been performed so far for HiPIMS W-C (separated W and C targets). The resulting coating properties were mainly analyzed by nano-hardness testing and X-ray diffraction. In general, the W₂C phase prevailed in tungsten-rich coatings with pulsed bias, leading to slightly higher tungsten contents. Hardness reached maximum values of up to 35 GPa in the center region between the two segments, where a mix of W₂C and WC_1-x phases occurs. With pulsed bias, voltage hardnesses are slightly higher, especially for tungsten-rich films. In those cases, compressive stress was also found to be higher when compared to constant bias. Erosive wear testing by blasting with alumina grit showed that the material removal rate followed basically the coating’s hardness but surprisingly reached minimum wear loss for W₂C single-phase films just before maximum hardness. In contrast to previous findings, low friction that requires higher carbon contents of at least 50 at. % is not favorable for this type of wear. Full article

Metal-ceramic crowns and bridges provide a stable and aesthetic tooth reconstruction. Hot pressing of veneering ceramics to metal substructure minimizes the formation of pores. Within the oral cavity, prosthetic structures are exposed to thermal stress. The study examines the influence of temperature changes on the quality and durability of the metal-ceramic bond using thermocyclic loading. Prior to the ceramic pressing, 40 cylindrical alloy specimens (height: 15 mm, diameter: 7 mm) were treated with abrasive blasting using Al₂O₃ (250 µm) or SiC (250 µm). They were divided into four groups: two control groups (sandblasted with Al₂O₃ or SiC) and two groups subjected to thermocyclic simulation. The ceramic-to-metal bond strength was measured with a shear test before and after thermocyclic loading. A statistically significant reduction in the bond strength between the metal substructure and the pressed ceramic was found after thermocyclic exposure. The bond strength decreased by 57% for Al₂O₃ sandblasted specimens and 36% for those sandblasted with SiC, as against the control group. This indicates that thermocycling weakens the bond between the metal alloy and pressed ceramic. The SiC blasting of the cobalt-chromium alloy results in a higher shear bond strength of the material connection after thermocyclic stimulation than the abrasive blasting with Al₂O₃. Full article

The article presents the results of numerical and experimental studies of a working nozzle for jet-abrasive machining of material surfaces. Nozzle designs with variable geometry were investigated. The aim of the study was to identify reserves for increasing the efficiency of the nozzle to ensure the energy efficiency of the jet-abrasive installation for sustainable production in the context of Industry 5.0. The implementation of numerical modeling made it possible to carry out a series of calculations for the considered nozzle designs using an air-abrasive mixture with flow visualization. The technological parameters of jet-abrasive machining were analyzed. A series of numerical and experimental studies were conducted using the principles of Industry 4.0. Two software packages were used for numerical studies. The results of the calculations that were obtained coincided quite well. Overall, the obtained results made it possible to adjust the settings of the pneumo-abrasive unit in order to get the proper roughness of the processed surface, opt for proper working nozzle design, and determine proper pressure and air consumption for the highest unit efficiency. In a series of studies, the authors proposed a mathematical model for determining the values of mass flow rates of the working medium in the nozzle. The analytical coefficients of the developed model have been obtained. In addition, an approach to determining the main parameters of abrasive blasting based on experimental data was developed. The results obtained were verified by comparing them with the results of experimental studies. It was found that to increase the efficiency of the Venturi nozzle, the outlet cross-section of the considered nozzles should be reduced, and the mass flow rate of the dispersed phase should not significantly affect the speed of the grains of sand at the nozzle outlet. Full article

This article presents research on advanced surface preparation methods for sintered carbides (WC-Co, grade B2) commonly used in the tool industry, particularly in the context of bonding these materials with C45 steel using adhesives. Sintered carbides are widely used due to their high hardness, wear resistance, and good ductility, making them ideal for manufacturing tools operating in harsh conditions. Traditional bonding methods, such as brazing and welding, often result in stresses and cracks. Adhesive bonding has therefore emerged as an effective alternative to mitigate these challenges. The research focuses on comparing the results obtained through modern surface treatment techniques, such as laser micro-texturing and plasma treatment, with traditional methods like grinding, abrasive blasting, and electrolytic etching. The influence of these methods on adhesion properties and the strength of adhesive bonds was evaluated through mechanical tests, including static shear and pull-off tests. An approximately 50% increase in the mechanical strength of adhesive joints was observed for surfaces treated with low-temperature plasma (operating voltage: 18 kV, flow of gasses: 20 l/min., treatment time: 60 s) and laser micro-texturing (infrared fiber laser, wavelength: 1064 nm (±5 nm), power: 20 W), as compared to mechanical grinding. The shear strength of the adhesive joints was equal to 32 MPa and 30 MPa on average in the case of treatment with low-temperature plasma made of helium and argon, respectively. The highest strength of an adhesive joint was equal to 34.5 MPa on average in the case of laser micro-texturing. Full article

The solder burrs on the 304V wire surface can easily scratch the vascular tissue during interventional treatment, resulting in complications such as medial tears, bleeding, dissection, and rupture. Abrasive blasting is often used to remove solder burr and obtain a smooth surface for the interventional device. This study conducted an abrasive blasting experiment to explore the effects of process parameters (air pressure, lift-off height, abrasive volume, and abrasive type) on processing time, surface roughness, and mechanical properties to reveal the material removal mechanism. The results indicated that the resin abrasive can remove the SAC burr and keep the 304V integrity due to the proper hardness and Young’s module. Impaction pits are the main material removal mode in abrasive blasting. The processing time decreases with the increase in air pressure. The surface roughness increases with the increase in abrasive volume. The primary and secondary factors affecting the surface roughness of the 304V wire after abrasive blasting are the abrasive type and air pressure, followed by the abrasive volume and lift-off height. Blasting leads to a decrease in yield strength, and Young’s modulus and the hardness of the abrasive will affect the tensile strength. This study lays a foundation for understanding abrasive blasting and different cutting mechanisms. Full article

Grit particles remaining on the substrate surface after grit blasting are generally considered to impair the thermal performance of thermal barrier coatings (TBCs). However, the specific mechanisms by which these particles degrade the multilayer structure of TBCs during thermal cycling have not yet been fully elucidated. In this study, the superalloy substrate was grit-blasted using various processing parameters, followed by the deposition of thermal barrier coatings (TBCs) consisting of a metallic bond coat (BC) and a ceramic top coat (TC). After thermal shock tests, local thinning or discontinuities in the thermally grown oxide (TGO) layer were observed in TBCs where large grit particles were embedded at the BC/substrate interface. Moreover, cracks originated at the concave positions of the TGO layer and propagated vertically towards BC; these cracks may be associated with additional stress imposed by the foreign grit particles during thermal cycling. At the BC/substrate interface, crack origins were observed in the vicinity of large grit particles (~50 μm). Full article

This study aimed to develop predictive models for rock hardness and abrasivity based on hyperspectral imaging data, providing valuable information without interrupting the mining processes. The data collection stage first involved scanning 159 rock samples collected from 6 different blasted rock piles using visible and near-infrared (VNIR) and short-wave infrared (SWIR) sensors. The hardness and abrasivity of the samples were then determined through Leeb rebound hardness (LRH) and Cerchar abrasivity index (CAI) tests, respectively. The data preprocessing involved radiometric correction, background removal, and staking VNIR and SWIR images. An integrated approach based on K-means clustering and the band ratio concept was employed for feature extraction, resulting in 28 band-ratio-based features. Afterward, the random forest regressor (RFR) algorithm was employed to develop predictive models for rock hardness and abrasivity separately. The performance assessment showed that the developed models can estimate rock hardness and abrasivity of unseen data with R² scores of 0.74 and 0.79, respectively, with the most influential features located mainly within the SWIR region. The results indicate that integrated hyperspectral data and RFR technique have strong potential for practical and efficient rock hardness and abrasivity characterization during mining processes. Full article

This article presents a machine vision system for measuring the arithmetic average roughness of shot- and sand-blasted surfaces. In the developed system, a digital microscope was used for capturing surface images after shot- and sand-blasting processes. The captured grayscale images were analyzed with the proposed algorithm using Otsu’s global thresholding and a size bandpass filter. The algorithm detected white regions associated with the specular reflection of light on a binary image, and then calculated the size of selected regions. One-way ANOVA was used to identify the relation between the size of the regions and the arithmetic average roughness of blasted surfaces. It was noted that the average size of white regions showed a linear relation to the arithmetic average roughness of both shot- and sand-blasted surfaces. Different abrasives (shot or sand) were found to bring about differences in the rate of change of the average size within a chosen roughness range. When a surface image with unknown roughness is given, it is possible to predict the arithmetic average roughness on the basis of the relation. This machine vision system enables the fast and low-cost roughness measurement of shot- and sand-blasted surfaces. Thus, it could be useful in a quality inspection for shot- and sand-blasting. Full article

Dry ice blasting is a technology that has been widely studied and applied in different industrial sectors as an alternative to the use of solvent, water, or abrasive spraying methods. It is a CO₂ spraying system capable of balancing efficiency and sustainability with a wide variety of equipment available on the market. This study analyses and compares cryo-cleaning equipment manufactured by pioneering companies in the cryogenic industry. Based on data sheets, safety data sheets, and contact with manufacturers, a quantitative comparative study has been carried out. The aim of this study is to identify those with the best performance, efficiency, and adaptability to operational and environmental requirements. The results reflect the strengths and weaknesses of the equipment in terms of occupational safety and operability. These have been discussed and evaluated, recognising improvements of this technology, which is capable of removing surface layers of different natures without altering the underlying substrate. Full article

Background: In patients undergoing surgery for oral cancer, soft support materials are used to minimise trauma to the soft tissues. Silicone-based liners are widely used in prosthetic dentistry. A prerequisite for long-term Adhesion of the liner to the denture base is largely dependent on the surface preparation of the denture material. Objectives: The aim of the present study was to investigate whether surface preparation of the acrylic material by sandblasting increases the adhesion of the silicone support material to the acrylic denture plate. Material and Methods: The study included adhesion testing of four silicone-based soft cushioning materials (Silagum Comfort, Elite Soft Re-lining, Ufi Gel SC, Mucopren Soft) on a total of 270 samples. Each material was tested on 15 samples. Three subgroups with different surfaces were separated: 1 raw—standard surface treatment with a cutter, and 2 sandblasted, with 100 and 350 µm alumina grain at 90°. The samples were subjected to seasoning: 24 h and six weeks. The adhesion force of silicone to acrylic was measured by performing a tensile test using a universal two-column testing machine. Results: The highest bond strength was recorded for Silagum on the surface prepared using 100 µm abrasive and seasoned for 6 weeks (291.5 N). The smallest among the maximum forces was recorded for the Mucopren material (81.1 N). For the Mucopren system with a raw and sand-blasted surface (350 µm), the adhesion strength increased after six weeks. In contrast, the durability of the joint decreased for the 100 µm sandblasted surface. The Elite material exhibited similar values for maximum forces (271.8 N) and minimum forces (21.1 N). The highest strength (226.1 N) was recorded for the sample from the group prepared with 350 µm abrasive and seasoned for 24 h. The lowest value (72.6 N) occurred for the sample from the group with 100 µm abrasive and seasoned for 6 weeks. Conclusions: Sandblasting of acrylic plastic improves adhesion to selected relining silicones. 2. The size of the abrasive employed has an impact on the adhesion between the acrylic plastic and the bedding silicone. 3. In the case of some relining systems (Mucopren), an increase in roughness through sandblasting has the effect of reducing the durability of the bonded joint. Full article

Denture fractures are a common problem in dental practice, and their repair is considered a first option to restore their functional properties. However, the inter-material resistance may become compromised. Typically, the bond between these materials weakens. Therefore, various surface treatment methods may be considered to enhance their mechanical properties. Poly(methyl methacrylate) (PMMA) heat-polymerized resin (HPR) was used as the repaired material, cold-polymerized material (CPR) for the repairs, and different variants of alumina abrasive blasting (AB), methyl methacrylate (M), ethyl acetate (EA), methylene chloride (CH), and isopropyl alcohol (IA) treatments were applied. Finally, combined surface treatments were chosen and analyzed. Surface morphologies after treatments were observed by scanning electron microscopy and the flexural, shear, and impact strengths were tested. AB and chemical treatment with CH, M, and EA was used to improve all mechanical properties, and further improvement of the properties could be achieved by combining both types of treatments. Varied changes in surface morphologies were observed. Treatment with IA yielded less favorable results due to the low impact strength. The best results were achieved for the combination of AB and CH, but during the application of CH it was necessary to strictly control the exposure time. Full article