Sandblasting Research Articles

Investigation of mechanical properties and microstructure characterisation of MMA-MIG-TIG-SAW welded EN8 steel joints via shot blasting method

The industries of energy, transportation, and other engineering components all benefit greatly from the use of medium carbon (C) steel EN8. For these applications, welding is typically used to join the material. Conventionally welded joints, however, struggle to meet the exacting standards of industrial applications. In this comprehensive study, the tensile strength, microhardness, and microstructure of joints made of medium C EN8 steel using manual metal arc (MMA), metal inert gas (MIG), tungsten inert gas (TIG), and submerged arc (SAW) welding were investigated. These weld joints were then subjected to the shot blasting method to determine the effect on the mechanical properties of these weldments, Different response characteristics have been studied in relation to the shot blasting with various time periods. A detailed characterisation of the samples has been carried out optical microscopy, surface electron microscopy (SEM), energy dispersive spectroscopy (EDS), optical emission spectroscopy (OES), microhardness, and tensile testing with fractographical analysis. The maximum percentage increase in the microhardness in fusion zone (FZ) occurred in case of TIG welded specimens, i.e. 29.63% after 25 min of abrasive blasting period. However, the maximum change in the tensile strength, i.e. 10.53% has been observed for MMA welded specimens after 15 min of abrasive blasting period. Microstructural analysis revealed TIG has a columnar dendritic structure, MIG and SAW have an equiaxed dendritic structure. MMA has a cellular dendritic structure. The outcomes revealed that abrasive blasting improves the mechanical characteristics of industrial MMA, MIG, TIG, and SAW welded specimens.

Laser Processing of Polyimide and Molybdenum Substrates for Extreme Environment Electronics

A desire in today’s electronic packaging technologies is to create more dense electronic packaging schemes. One method to achieve more dense electronic package integration is to use three-dimensional interconnects to minimize interconnect physical dimensions. Three-dimensional interconnect technologies, such as interposers, require a method of connecting electronics to electronic packages vertically. Thru silicon vias are a widely studied and explored vertical interconnect technology used in a variety of electronic packaging applications. Though silicon has high material hardness, the brittle nature of silicon substrates is a concern for robustness and reliability. These concerns only increase when the desired interconnect application is in extreme environments, such as cryogenic temperatures. A potential alternative to silicon in thru-via applications in extreme environments is molybdenum. Molybdenum is a commonly used material in many applications, such as automotive and aerospace, and has high material strength. Molybdenum is also a low coefficient of thermal expansion material, comparable to silicon, which in combination with high material strength lends to high reliability at extreme temperatures. A challenge of working with refractory metals such as molybdenum is that conventional CNC machining techniques require the use of machining coolants that may not be compatible with fabricated electronics and/or processes can become costly due to tool wear and the need for specialized equipment. Additionally, using molybdenum as a thru-via substrate requires the need for an electrically insulated layer, such as polyimide, within drilled molybdenum thru-holes to prevent the molybdenum substrate from shorting via connections. One potential solution to the above challenges is developing laser processing techniques to cut and drill molybdenum and polyimide. Laser processing is becoming a preferred method for inexpensive prototyping with high resolution and design versatility. This work seeks to meet the challenges described by developing laser cutting and drilling techniques for both molybdenum and polyimide for the use in cryogenic applications. This work will describe two laser processing configurations utilizing two different lasers to laser machine molybdenum and polyimide. This work will first describe the process strategies of laser cutting and drilling molybdenum as a stand-alone substrate. Aspects of laser processing on molybdenum, such as pattern repetitions and scanning speeds, will be described. Process parameter variations will be compared directly and evaluated. Additionally, post-laser processing steps, such as abrasive blasting, will be described and discussed. Next, the fabrication steps to achieve an insulating layer of polyimide in laser drilled holes as well as on each surface of the molybdenum will be detailed. Once polyimide has been cured, laser processing parameters to realize thru-holes in the polyimide-filled molybdenum drills will be presented. Adhesion of polyimide on the molybdenum substrate will be verified and demonstrated through the use of confocal scanning acoustic microscopy before and after polyimide laser processing. Cryogenic performance will be verified by completing confocal scanning acoustic microscopy after submersion in liquid nitrogen (~77 K) and compared with the pre-submersion microscopy images. Processes detailed in this work will open opportunities for future development of molybdenum-based interconnect structures for use in cryogenic applications. Acknowledgement We thank the Alabama Micro/Nano Science and Technology Center (AMNSTC) for providing access to fabrication and characterization facilities used in this work.

Influence of hydrothermal aging on the shear bond strength of 3D printed denture-base resin to different relining materials

ObjectivesThis study evaluated the repairability of three-dimensional printed (3DP) denture bases based on different conventional relining materials and aging. Material and methodsThe groups for surface characterization (surface-roughness and contact-angle measurements) were divided based on the denture base and surface treatment. Shear bond strength test and failure-mode analysis were conducted by a combination of three variables: denture base, relining materials, and hydrothermal aging (HA). The initial characterization involved quantifying the surface roughness (n = 10) and contact angle (n = 10) of denture base specimens with and without sandblasting (SB) treatment. Four relining materials (Kooliner [K], Vertex Self-Curing [V], Tokuyama Rebase II (Normal) [T], and Ufi Gel Hard [U]) were applied to 3DP, heat-cured (HC), and self-cured (SC) denture-base resin specimens. Shear bond strength (n = 15) and failure-mode analyses (n = 15) were performed before and after HA, along with evaluations of the fractured surfaces (n = 4). Statistical analyses were performed using a two-way analysis of variance (ANOVA) for surface characterization, and a three-way ANOVA was conducted for shear bond strength. ResultsThe surface roughness peaked in HC groups and increased after SB. The 3DP group displayed significantly lower contact angles, which increased after treatment, similar to the surface roughness. The shear bond strength was significantly lower for 3DP and HC denture bases than for SC denture bases, and peaked for U at 10.65 ± 1.88 MPa (mean ± SD). HA decreased the shear bond strength relative to untreated samples. Furthermore, 3DP, HC, and SC mainly showed mixed or cohesive failures with V, T, and U. K, on the other hand, trended toward adhesive failures when bonded with HC and SC. ConclusionThis study has validated the repairability of 3DP dentures through relining them with common materials used in clinical practice. The repairability of the 3DP denture base was on par with that of conventional materials, but it decreased after aging. Notably, U, which had a postadhesive application, proved to be the most effective material for repairing 3DP dentures.

Precipitation mechanism of dispersed carbide in a gear carburizing layer and its effect on properties

AbstractHeat treatment is carried out on 20MnCr5 gear steel using a cycle carburizing process. The dispersed carbide precipitation mechanism in the carburized layer of 20MnCr5 gear steel is revealed, and the metallographic organization, microhardness, wear resistance, and fatigue properties are tested. The precipitation mechanism of two kinds of dispersed carbides at grain boundary and inside grain in carburized layer of gear steel was observed by experiment. The size of dispersed carbide particles is 0–5 μm, and 90% of the dispersed carbide is appropriately smaller than 1 μm. Compared to gears without dispersed carbide, gears with dispersed carbide have high microhardness within a 0.4 mm depth below the surface and a low friction coefficient. It has been verified by bench test that the presence of diffuse carbides dramatically improves the fatigue life of the gears after shot blasting and shot peening.

Improving Bond Strength of Translucent Zirconia Through Surface Treatment With SiO2-ZrO2 Coatings.

Translucent monolithic zirconia ceramics have been applied in dental clinics due to their esthetic translucent formulations and mechanical properties. Considering inherent ceramic brittleness, adhesive bonding with resin composite increases the fracture resistance of ceramic restorations. However, zirconia is a chemically stable material that is difficult to adhesively bond with resin. To investigate the influences of SiO2-ZrO2 coatings on adhesive bonding of zirconia and the surface characterization of those coatings. Translucent zirconia discs were classified into groups based on surface treatments: CT (control), SB (sandblasting), C21(SiO2:ZrO2=2:1), C11(SiO2:ZrO2=1:1), and C12 (SiO2:ZrO2=1:2) (n=10). Surface characterization of coatings on zirconia were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface roughness assessment (Ra), X-ray diffraction (XRD), water contact angle (WCA), translucency parameter (TP), and shear bond strength (SBS). Two-way ANOVA for shear bond strength results and ANOVA for Ra and WCA were performed. SEM images revealed SiO2 islands on zirconia disks coated with SiO2-ZrO2. Surface roughness of C12, C11, and C21 groups was significantly larger than those of groups SB and CT (p<0.05). XRD results showed that phase transformation of zirconia disks was detected only in the SB group. In addition, SiO2-ZrO2 coatings reduced WCA. The translucency decreased only in group C21. Group C11 showed the highest shear bond strength under both aging conditions. SiO2-ZrO2 coating is a promising method to enhance the adhesive resin bonding of translucent zirconia without causing phase transformation of translucent zirconia.

Design of special vacuum fan for use in the ship scraping process

The outer surfaces of ships should be smooth for efficiency and safety. With the scraping process, the performance of the ship is increased and the possible negative effects are minimized. One of the biggest causes of corrosion (abrasion) that may occur over time is rough surfaces. The scraping process, which is one of the most important processes in shipyards, is very laborious, and at the same time, the dust and chemical wastes that occur during the process reveal extremely harmful results for the environment. Thus in this work the optimum design and operating parameters (best efficiency) of the fan specially designed for the removal of dust and solid wastes from the environment with a closed system, which is generated during the surface cleaning process using abrasive blasting materials were obtained. Taguchi experimental design method was applied. Afterwards, the effect of which parameter on the results was determined with the Anova Statistical Analysis method. The same values were obtained in the results obtained by using both the experimental studies obtained by the classical method and the statistical data of the fans designed within the scope of the study, of which 9 prototypes were manufactured. The values of 100 Hz frequency, suction pipe diameter of 110 mm and wing width of 650 mm were determined as the most optimum results.

The effect of surface treatment and low-temperature degradation on flexural strength of additive manufactured zirconia

This study aimed to assess the effect of low-temperature degradation (LTD) and surface treatment on the flexural strength of additive-manufactured (AM) zirconia by comparison to subtractive-manufactured (SM) zirconia. Disc-shaped zirconia specimens were fabricated using AM and SM technology, and each group was assigned to 3 subgroups according to the type of surface treatment: control, sandblasting (SB), and 9% hydrofluoric acid etching (HF). The groups were then further divided into 2 subgroups: unaged and aged. Biaxial flexural strength, crystal phase, surface topography, and surface roughness were measured to evaluate the mechanical properties. Statistical analyses were performed with 3-way ANOVA, followed by the comparison of means with Bonferroni post hoc analyses. The means and standard deviations of the biaxial flexural strength and Weibull parameters were calculated with descriptive statistics. All SM groups showed significantly greater flexural strength than the AM groups (p < .05), and LTD did not affect flexural strength except for the SMHF group (p < .05). After LTD, monoclinic phases (m-phase) were found in all groups, and SEM images showed grain pullout due to zirconia volume expansion in both control groups. Sandblasting significantly affected flexural strength (p < .05), whereas the HF group did not affect flexural strength except in the SMHF group after LTD (p < .05). No significant difference was observed in the surface roughness of AM compared to SM groups conditioned with the same surface treatment regardless of LTD. AM zirconia has comparable mechanical properties to SM zirconia, regardless of low-temperature degradation and surface treatment, which indicates the potential of the AM technique for clinical applications.

Experimental testing of GCr15 bearing steel with different surface treatments as passive friction energy-dissipative shims

The seismic performance of buildings can be improved by adding supplemental damping using friction dampers. The friction behavior of the metallic shims becomes more stable with increasing surface hardness ratio between the friction pair. However, as hardness increases, metallic materials tend to become more brittle, which increases the risk of accidental failure. This study investigated the performance of a friction energy dissipator using bearing steel (GCr15) treated by a grinding-strengthening process, a special manufacturing technology for bearings steel commonly used in mechanical engineering. Two base materials, Q355 and B450, were additionally compared with GCr15. Each base material used three different surface treatments, i.e., cleaned surface (CS), sand-blasting (SB), and grinding-strengthen (GS) treatments. The surface hardness of Q355-GS, B455-GS, and GCr15-GS increased by 13.62 %, 17.38 %, and 19.71% compared to their base materials, while sand-blasting didn’t have an increased effect on surface hardness. The nine specimens were quasi-statically tested to investigate the effect of surface treatment on the friction behavior of the metallic shims. For the three Q355-like and three B450-like specimens, the wear mechanism mixed abrasive and adhesive wear. The GCr15-CS experienced contact fatigue failure, while the GCr15-SB and GCr15-GS exhibited abrasive wear resulting in standard rectangular hysteretic loops with a high degree of coincidence. The friction performance of GCr15-GS was the best among the nine friction shims, because it has less loss in friction coefficient and strength during fatigue loading, the least fluctuation in bolt force, and the smallest degradation and coefficient of variation in friction strength.

Poly-Ether Ether-Ketone Post Conditioned with Sulfuric Acid, Rose Bengal Activated by Photodynamic Therapy and Sandblasting on Pushout Bond Strength to Radicular Dentin Luted with Methyl Methacrylate and Composite-Based Cement.

Objective: Assessment of post surface conditioners [sulfuric acid (SA), Rose Bengal (RB), and sandblasting (SB)] and different luting cements [methyl methacrylate (MMA)-based cement and composite-based cement] on pushout bond strength (PBS) of poly-ether ether-ketone (PEEK) post bonded to canal dentin. Materials and methods: Endodontic treatment was performed on 120 single-rooted human premolar teeth. The preparation of the post space was performed and 4 mm of gutta-percha was retained in the apical region of the root. One hundred and twenty PEEK posts were fabricated from a PEEK blank utilizing a Computer aided design-Computer aided manufacture (CAD-CAM) system. The PEEK posts were allocated randomly into four groups based on post surface conditioning (n = 30). Group A: SA, Group B: RB, Group C: SB, and Group D: No conditioning (NC). Each group was further divided into two subgroups based on the luting cement used for bonding (n = 15). Group A1, B1, C1, and D1 specimens were cemented using composite-based resin cement. However, Group A2, B2, C2, and D2 posts were luted with MMA-based resin cement. PBS assessment using a universal testing machine was performed. Failure modes were analyzed under a stereomicroscope. The data relating to the effects of surface treatment and luting types of cement were analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc test (p = 0.05). Results: Coronal section of Group B2: RB+Super-Bond C&B [9.61 ± 0.75 megapascals (MPa)] displayed the highest bond scores of PEEK after root dentin. Whereas it was also discovered that Group D1: NC+Panavia®V5 (2.05 ± 0.72 MPa) presented the lowest PBS scores. Intergroup comparison analysis revealed that Group A2: SA+Super-Bond C&B and Group B2: RB+Super-Bond C&B displayed no significant difference in their bond scores. Conclusions: RB and SA possess the potential to be used as a PEEK post conditioner. MMA-based cement displayed better performance than composite-based cement.

Optimization of silica sand abrasive parameters on machining of glass plate in AJM using Taguchi method

Fine abrasive blasting of glass materials is widely used in the micro-electromechanical systems and biomedical industries. Creating high-quality holes in these materials requires precise control of the input parameters. In this study, experimental and optimization study was performed to assess the impact of various parameters during abrasive jet machining (AJM) on material removal rate (MRR), where SiC is used as the abrasive particle. Experiments were performed in line with the Taguchi experimental design where L9 orthogonal array was selected to understand the influence of nozzle diameter, standoff distance (SOD), and work piece (glass) thickness on MRR. It was observed that the material removal rate was proportional to the abrasive particles’ kinetic energy. Among the considered parameters viz. nozzle diameter, standoff distance, and work piece thickness, nozzle diameter exerted most significant effect on MRR followed by SOD and work piece thickness. Highest MRR, 0.0143 g/sec, was observed at SOD of 2.05 mm, nozzle diameter of 3 mm and work piece thickness of 4 mm. The researchers can follow the same methodology and determine the efficiency of industrial wastes possessing high hardness as abrasive particles, thereby, contributing additionally towards ecology protection.

Internal surface modification of additively manufactured macroporous TiAl6V4 biomimetic implants via a calciothermic reaction-based process and osteogenic in vivo responses.

Three-dimensional macroporous titanium-aluminum-vanadium (TiAl6V4) implants produced by additive manufacturing (AM) can be grit blasted (GB) to yield microtextured exterior surfaces, with additional micro/nano-scale surface features provided by subsequent acid etching (AE). However, the line-of-sight nature of GB causes the topography of exterior GB + AE-modified surfaces to differ from internal GB-inaccessible surfaces. Previous in vitro studies using dense TiAl6V4 substrates indicated that a nonline-of-sight, calciothermic-reaction (CaR)-based process provided homogeneous osteogenic nanotextures on GB + AE surfaces, suggesting it could be used to achieve a homogeneous nanotopography on external and internal surfaces of macroporous AM constructs. Macroporous TiAl6V4 (3D) constructs were produced by direct laser melting and modified by GB + AE, with the CaR process then applied to 50% of constructs (3DCaR). The CaR process yielded nanoporous/nanorough internal surfaces throughout the macroporous constructs. Skeletally mature, male Sprague-Dawley rats were implanted with these constructs using a cranial on-lay model. Prior to implantation, a Cu++-free click hydrogel was applied to half of the constructs (3D + H, 3DCaR + H) to act as a challenge to osseointegration. Osseointegration was compared between the four implant groups (3D, 3DCaR, 3D + H, 3DCaR + H) at 4w. 3D + H implants exhibited lower bone volume (BV) and percent bone ingrowth (%BI) than the 3D implants. In contrast, osseointegrated 3DCaR + H implants had similar BV and %BI as the 3DCaR implants. Implant pull-off forces correlated with these results. In vitro analyses indicated that human bone marrow stromal cells (MSCs) exhibited enhanced production of osteoblast differentiation markers and factors associated with osteogenesis when grown on CaR-modified 3D substrates relative to control (TCPS) substrates. This work confirms that the CaR process provides osteogenic nanotextures on internal surfaces of macroporous 3D implants, and suggests that CaR-modified surfaces can promote osseointegration in cases where osteogenesis is impaired.

Influence of surface treatment on metal dusting resistance of welds

AbstractWelds of the commercial Ni‐based alloys 602 CA, 699 XA, 601 and 690 were exposed under harsh metal dusting conditions. The pit formation was compared for as‐welded, brushed, ground, glass bead blasted, steel shot peened and dry cathodic pickled surfaces. Surface treatments were applied by industrial partners. When (stainless) steels were involved in the surface treatment, Fe contaminations acted as catalyst sites for pit initiation. A fast metal dusting attack was also observed on dry cathodic pickled samples. A beneficial effect was attributed to deformation of the sub‐surface zone, as it provides diffusion paths for oxide formers (by grinding and glass bead blasting). In the same region, formation of α‐Cr (BCC) precipitates was observed. The best performance was found for samples where the weld bead was fully flattened by grinding to P40 grit. In addition, it was demonstrated that on‐site slurry aluminization further enhances the resistance against metal dusting attack.

Influence of surface pretreatment on the bonding mechanism and mechanical properties of AA5052/CFRP friction stir spot welded joint

Hybrid structure of aluminum alloy and carbon fiber reinforced polymer (CFRP) has been widely applied in the automotive industry for energy saving, emission reduction and structural light weighting. The large differences in physicochemical properties and metallurgical incompatibility between metals and CFRP easily generate interface separation defect at the joint interface. In this study, sulfuric acid anodizing (SAA), sandblasting (SB), and sandblasting + sulfuric acid anodizing (SB + SAA) pretreatments were used to modify the surface of 5052 aluminum alloy (AA5052). Friction stir spot welding was employed to join the modified AA5052 to carbon fiber reinforced polyether ether ketone composites (CF-PEEK). The tensile shear load for SAA, SB, and SB + SAA pretreatment joints were 2076 N, 3112 N, and 2798 N, respectively. SB pretreatment eliminated the interface separation defect and obtained hybrid joints with excellent mechanical properties. The results of microstructural analysis revealed that SB pretreatment removed the oxide layer on the surface of aluminum alloy and increased the surface roughness, which promoted the mechanical interlocking and adhesive bonding effect between AA5052 and CF-PEEK. The distribution of alloying elements showed that a diffusion layer of Al and C formed at the joint interface. This demonstrated the good bonding of aluminum alloys with CF-PEEK. Except specimens after SB pretreatment, the other specimens fractured along the interface separation defect. SB pretreatment eliminated the interface separation defect and changed the fracture path, leading to the excellent mechanical properties of the joint.

Development of ultra-low cycle fatigue life prediction model for structural steel considering the effects of surface roughness, loading frequency, and loading amplitude

Abrasive blast cleaning is often done for steel structures before applying various protective coatings, which produces rough surfaces with changes in fatigue properties. This problem has been addressed in the low- and high-cycle fatigue regimes; however, the effect of surface roughness in combination with different loading parameters on the ultra-low cycle fatigue (ULCF) life has not been reported thus far. To this aim, a total of 59 ULCF tests on designed specimens of SM400 steel with five levels of surface roughness were performed under various loading frequencies and displacement amplitudes. The analysis of experimental results indicates a substantial reduction in fatigue life with an increase in the surface roughness and loading amplitude and a decrease in the loading frequency. Additionally, the strength degradation, dissipation energy, and load–displacement curves are discussed in detail. With the use of experimental data, a new life prediction model characterizing the combined effects of surface roughness, loading frequency, and loading amplitude on the ULCF life is proposed. Moreover, the proposed model is validated by predicting the fatigue life under variable and constant loading amplitude patterns. Comparison between experimental and theoretical results shows that the proposed model accurately estimates the ULCF life within an error band of ±15%, with a reasonable selection of model parameters.

Effect of Shot Blasting on the Boriding Kinetics of AISI 316L Stainless Steel

Effect of Shot Blasting on the Boriding Kinetics of AISI 316L Stainless Steel

Non-thermal atmospheric pressure plasma treatment increases hydrophilicity and promotes cell growth on titanium alloys in vitro

Most medical implants are made of titanium. When titanium is exposed to air for a long time, hydrocarbons are deposited and the surface becomes hydrophobic. Cell attachment is important for bone ingrowth to occur on the implant surface, and hydrophilicity can enhance this. We examined whether non-thermal atmospheric pressure plasma treatment could increase the hydrophilicity of the titanium surface. Samples coated with four widely used coating types [grit blasting, micro arc oxidation (MAO), titanium plasma spray (TPS), and direct metal fabrication (DMF)] were treated with plasma. Each of the four surface-treated samples was divided into groups with and without plasma treatment. We analysed wettability by surface analysis and evaluation of contact angles, cell proliferation, and adhesion using scanning electron microscopy (SEM), confocal laser scanning microscopy, absorbance tests, and alkaline phosphatase (ALP) activity assay; four different Ti6Al4V surface types were compared. After plasma treatment, the contact angle was reduced on all surfaces, and the carbon content was reduced on all surfaces based on X-ray photoelectron spectroscopy (XPS) surface analysis. Under confocal laser scanning, the cell layer was thicker on the plasma-treated samples, especially in groups TPS and DMF. Cell proliferation was 41.8%, 17.7%, 54.9%, and 83.8% greater for the plasma- than non-plasma-treated grit blasting, MAO, TPS, and DMF samples, respectively. Hydrophilicity increased significantly under plasma treatment, and biological responsivity was also improved.

An investigation into the effects of prosthesis relevant surfaces on the formation of Staphylococcus aureus biofilms

The aim of this study was to investigate the effects prosthesis relevant surfaces and finishes have on the formation of Staphylococcus aureus (S. aureus) biofilms, the leading causative pathogenic bacteria of periprosthetic joint infection (PJI). Microbiological biofilm analysis was conducted to quantify S. aureus biofilm growth on prosthesis relevant surface coatings and finishes. Through the use of a CDC Biofilm Reactor (CDC-BR), biofilms were grown under constant shear conditions on three different titanium surface finishes, including Plasma Spray (PS), Grit Blasted (GB) and an As-fabricated (AF) surface used for comparative and control purposes. Advanced metrological techniques were applied to characterise each surface. This advanced approach to surface characterisation, including functional volume parameters has been carried out to provide a detailed quantifiable description of the surface and one that better relates to the nature of growth upon a surface. Results show that the PS surface exhibits a significant increase in biofilm growth in comparison to the GB and AF surfaces, with the AF surface showing the lowest amount of biofilm growth. Additionally, the morphology of the features of the PS coating allows for the biofilm accumulation to flourish in the re-entrant features across its topography. These findings highlight the difficulties of biofilm eradication and further complicate the design process of prosthetics, where features implemented to promote osseointegration simultaneously offer favourable locations for bacterial cell attachment and subsequent biofilm development, leading potentially, to PJI. There is a general consensus throughout literature regarding an apparent trend between an increase in Sa and an increase in biofilm formation (Zheng et al 2021 Frontiers in Bioengineering and Biotechnology 9 643722; Bridgens et al 2015 Surface and Coatings Technology 284; James et al 2019 Aesthetic Plast. Surg. 43 490–497). This study has shown that whilst this may generally be the case, the location of this surface area increase within the topography may be a more important observation.

Surface Modification Methods of Self-Cured Acrylic Resin Repaired with Resin Composite Using a Universal Adhesive

This research study’s purpose was to evaluate the mechanical and chemical surface treatment methods for self-cured acrylic resin repaired with a resin composite employing a universal adhesive agent. Eighty self-cured acrylic resins were built and designed into eight groups of ten specimens and surface conditioned using sandblasting (SB) and/or with methylmethacrylate monomer (MMA) and/or universal adhesive (UA) as follows: Group 1, non-surface modified; Group 2, SB; Group 3, UA; Group 4, SB + UA; Group 5, MMA; Group 6, SB + MMA; Group 7, MMA + UA; Group 8, SB + MMA + UA. A template was put on the specimen center, and the pushed resin composites. Mechanical testing machinery was used to examine the samples’ shear bond strength (SBS) values. To examine failure patterns, the debonded specimen surfaces were examined using a scanning electron microscope. The one-way ANOVA method was used to evaluate these data, and Tukey’s test was used to determine the significance level (p &lt; 0.05). The highest SBS was obtained in Group 8 (27.47 ± 2.15 MPa); however, it was statistically equivalent to Group 7 (25.85 ± 0.34 MPa). Group 1 (4.45 ± 0.46 MPa) had the lowest SBS, but it was not statistically significant compared to Group 2 (5.26 ± 0.92 MPa). High SBS values were frequently correlated with cohesive patterns. The application of MMA prior to UA is the best method for increasing the SBS between self-cured acrylic resin and resin composite interfaces. However, the use of SB is not significantly different from not using SB.

Performance and Durability of Non-Stick Coatings Applied to Stainless Steel: Subtractive vs. Additive Manufacturing.

This study compares subtractive manufacturing (SM) and additive manufacturing (AM) techniques in the production of stainless-steel parts with non-stick coatings. While subtractive manufacturing involves the machining of rolled products, additive manufacturing employs the FFF (fused filament fabrication) technique with metal filament and sintering. The applied non-stick coatings are commercially available and are manually sprayed with a spray gun, followed by a curing process. They are an FEP (fluorinated ethylene propylene)-based coating and a sol-gel ceramic coating. Key properties such as surface roughness, water droplet sliding angle, adhesion to the substrate and wear resistance were examined using abrasive blasting techniques. In the additive manufacturing process, a higher roughness of the samples was detected. In terms of sliding angle, variations were observed in the FEP-based coatings and no variations were observed in the ceramic coatings, with a slight increase for FEP in AM. In terms of adhesion to the substrate, the ceramic coatings applied in the additive process showed a superior behavior to that of subtractive manufacturing. On the other hand, FEP coatings showed comparable results for both techniques. In the wear resistance test, ceramic coatings outperformed FEP coatings for both techniques. In summary, additive manufacturing of non-stick coatings on stainless steel showed remarkable advantages in terms of roughness, adhesion and wear resistance compared to the conventional manufacturing approach. These results are of relevance in fields such as medicine, food industry, chemical industry and marine applications.

Influence of engineered roughness microstructures on adhesion and turbulent resuspension of microparticles

From microplastics resuspending into the atmosphere to earth particles left behind during extraterrestrial explorations, the resuspension of microparticles by a turbulent gas flow occurs in many natural, environmental and industrial systems. Wall surfaces, onto which particles initially adhere, are rarely smooth and this surface roughness affects particle resuspension. Available experimental data on particle resuspension have been obtained with substrates, whose surfaces are either unaltered or manually abraded with, for instance, sand blasting. In these experiments, the roughness elements span a wide size range and are in-homogeneously distributed in space. Surface functionalization is a modern technique allowing the precise fabrication of a wall surface with well-characterized microstructures, hence reducing the asperity randomness associated with conventional abrasion techniques. Taking advantage of surface functionalization, we present here a new set of reference data, where the wall asperities are represented by a structured arrangement of micropillars and microcubes. Adhesion force measurements and particle remaining fraction against gas velocity, at Reynolds number up to 8000, are reported for one reference and two artificially roughened substrates. Laboratory measurements show that the microasperities have little to moderate effect on the mean adhesion force and the threshold velocity, at which half of the 100-μm particles resuspend. The standard deviations are, however, much more affected. The presented results will primarily contribute to the improvement of resuspension models, which until now rely on a simplified representation of the surface roughness elements. The presented measurements are highly compatible with such models, which involve elementary roughness features, such as hemispherical asperities superimposed with a flat plate.