Roughness Values Research Articles

Quantitative in-vitro evaluation of enamel surface roughness following two debonding procedures using laser scanning confocal microscope.

The objective of the in vitro study was to evaluate the impact of two adhesive removal techniques on the surface roughness of the human enamel surface using laser scanning confocal microscopy (LSCM). Forty healthy first upper molar teeth were included in this experiment (20 teeth per each group). T0 measurement of surface roughness parameter of the teeth were conducted using LSCM. The teeth were bonded with metal brackets. Following 24 hours of sample storage in distilled water, the brackets were debonded. A modified adhesive remnant index (ARI) was used to exclude samples with below 90% adhesive remnants on their surface. The remaining 36 teeth were then randomly divided into two groups (18 teeth per group) with the following debonding procedures: group TC (single stage method using a Smoozie tungsten carbide bur) and group TCP (two stage method using a Smoozie tungsten carbide bur, followed by a Smoozie polisher). The time needed for complete adhesive removal was recorded and T1 surface roughness measurements were conducted again after adhesive removal using LSCM. Significantly higher surface roughness values were recorded in group TC, compared to group TCP (P<0.01). Method TCP, on the other hand, was significantly more time-consuming than method TC (P<0.01). Despite the fact that the two-stage method (group TCP) was more time consuming, the lower level of enamel surface roughness in this method suggests the superiority of this method.

Recent Contributions to the Development of Barrel End-Mill Machining Technologies for Titanium Alloys in the Aerospace Context

This study investigates the utilization of barrel end-mills in machining titanium alloys for aerospace applications. It involves a comprehensive review of the relevant literature and a preliminary experimental investigation, incorporating the influence of measurement direction on surface roughness and the behavior of cutting forces. The primary objective is to assess the performance and efficiency of these end-mills when machining challenging materials and to identify optimal cutting strategies. This paper emphasizes the significance of titanium alloys in the aerospace sector, due to their exceptional mechanical properties, and the problems encountered in their processing. It also highlights the advantages of barrel end-mills, such as enhanced accessibility and superior surface finish. Through a combination of literature review, practical experimentation under controlled conditions, and statistical analysis, this study investigates the surface roughness of the Ti-6Al-4V titanium alloy, confirming a significant difference between longitudinal and transverse roughness. The preliminary experiment revealed that the average values of longitudinal and transverse roughness were 0.237 µm and 0.263 µm, respectively. The coefficients of variation indicated a greater variation in longitudinal roughness (19.79%) compared to transverse roughness (18.61%). This study’s conclusions provide a solid foundation for future research into machining titanium alloys with barrel end-mills, contributing to the optimization of manufacturing processes and the enhancement of aerospace component performance.

Leveraging the nanotopography of filamentous fungal chitin-glucan nano/microfibrous spheres (FNS) coated with collagen (type I) for scaffolded fibroblast spheroids in regenerative medicine.

Numerous naturally occurring biological structures have inspired the development of innovative biomaterials for a wide range of applications. Notably, the nanotopographical architectures found in natural materials have been leveraged in biomaterial design to enhance cell adhesion and proliferation and improve tissue regeneration for biomedical applications. In this study, we fabricated three-dimensional (3D) chitin-glucan micro/nanofibrous fungal-based spheres coated with collagen (type I) to mimic the native extracellular matrix (ECM) microenvironment. These collagen-coated fungal nano/microfibrous spheres (C-FNS) were utilized to construct 3D scaffolded spheroids of human fibroblasts through suspension culture for tissue engineering and regenerative medicine. The particle sizes of C-FNS ranged from 1.4 to 3.25 µm (average: 2.27 ± 0.38 µm), with a porosity of 81.17 %. Field emission-scanning electron microscopy (FE-SEM) revealed that C-FNS comprised continuous chitin-glucan fibers with an average diameter of 363 ± 61 nm (range: 203-512 nm), exhibiting a highly interconnected structure. The reduced arithmetic average roughness (Ra) and root mean square roughness (Rq) values of C-FNS compared to uncoated FNS suggested that collagen coating reduced surface roughness, resulting in a smoother surface that enhanced hydrophilicity, crucial for mammalian cell adhesion and spheroid formation. Moreover, the in vitro cytocompatibility of C-FNS with fibroblasts was evaluated using a resazurin-based PrestoBlue assay, which demonstrated a time-dependent increase in the metabolic activity of C-FNS/fibroblast spheroids during suspension culture for up to 14 days. FE-SEM images of C-FNS/fibroblast spheroids further revealed enhanced adhesion and proliferation of fibroblasts on the nano/microfibrous mycelial architecture, accompanied by the secretion of ECM components and formation of multilayered cell sheets over the 14-day culture period. Similarly, an assessment of the hemocompatibility of C-FNS with erythrocytes revealed the non-hemolytic properties of the biomaterial. Overall, the interaction between collagen-coated fungal chitin-glucan nano/microfibrous structures and mammalian cells holds significant potential for the development of novel, sustainable biomaterials with tailored properties for a myriad of biomedical applications, including tissue engineering, regenerative medicine, drug screening, and wound healing.

Investigation of the Effects of Thermal Cycling and Surface Treatments on Interim Resin Materials Produced with Additive Manufacturing

This study aimed to compare the impact of thermal cycling on the flexural strength (σfs) of 3-dimensional (3D) printer resins and polymethyl methacrylate (PMMA). It also aimed to evaluate different surface treatment protocols and surface sealant applications on the surface roughness (Ra) and surface hardness (VHN) of the resins used. Rectangular (25�2�2 mm) and disc (Ø10�2-mm) specimens were fabricated from auto-polymerized PMMA, and 3D-printed resins were tested for mechanical properties (ISO 10477) using thermal cycling (n=10). Disc specimens were separated into three groups (n=10) based on the surface treatments: conventional sanding (C), disk polishing (P), and surface sealant coating (O). Ra and VHN values were statistically analyzed with the Kolmogorov Smirnov, Shapiro Wilk, Independent Samples t-test, Mann-Whitney test, one-way ANOVA test and Kruskal Wallis test (α =.05). A significant main effect was found on the flexural strength analysis for each of the two factors: thermal cycling procedure (p[0.001) and materials (p 0.001). A significant main effect was found on the surface roughness and hardness analysis for each of the two factors: surface treatment protocols (p[0.001) and materials (p[0.001). Based on the results; interim materials produced with 3D-printed resins have better mechanical properties than conventionally polymerized materials. Coated materials had lower surface roughness values than polished ones, and adding a surface sealant agent increased their hardness significantly.

Five-Axis Printing of Continuous Fibers on the Mold

This paper explores a five-axis printing method designed to improve the fabrication of continuous fiber-reinforced thermoplastic composites (CFRTPCs), essential for producing lightweight, complex structures in advanced manufacturing. Traditional CFRTPC placement techniques often face challenges with precision, scalability, and optimal fiber orientation, especially in customized, small-scale applications. The proposed five-axis printing technique overcomes these issues by enabling precise fiber orientation and the production of robust spatial structures using 3D-printed molds compatible with CFRTPCs. Validation through three-point bending and surface quality tests revealed that five-axis printed cylindrical-lattice samples, with fibers oriented at 45°, exhibited superior mechanical properties and surface quality. The five-axis printed samples achieved a load-to-weight ratio 27% higher than traditional samples and maintained their shape even under significant deformation. Surface quality improved significantly, with roughness values reduced from 37.63 µm to approximately 12 µm. This method advances CFRTPC applications in industries requiring complex, lightweight components.

Effect of mechanical instrumentation on titanium implant surface properties.

To assess the impact of mechanical decontamination using rotary brushes on the surface topography, elemental composition, roughness, and wettability of titanium implant surfaces. Four commercially available rotary brushes were used: Labrida BioClean Brush® (LB), i-Brush1 (IB), NiTiBrush Nano (NiTiB), and Peri-implantitis Brush (PIB). Seventy-five titanium discs with sandblasted, large-grit, acid-etched (SLA) surfaces were randomly assigned to five groups (n = 15): LB, IB, NiTiB, PIB, and a control group. Each disc was treated for 60 seconds with the respective rotary brush according to the manufacturer's instructions. Surface morphology was analysed using Scanning Electron Microscopy (SEM), surface elemental composition with Energy Dispersive X-ray (EDX), surface roughness via optical profilometry, and wettability with a droplet shape analyser. SEI analysis revealed morphological changes, including scratches, flattening, and loose titanium particles in the IB, PIB, and NiTiB groups, whereas the LB group preserved the original surface morphology. SEM-EDX analysis showed that LB, PIB, and NiTiB groups closely match the control elemental composition. However, IB groups showed significantly different composition. Surface roughness values in the IB, PIB, and NiTiB groups differed significantly from the control (p < 0.05), whereas the LB group had comparable roughness values (p > 0.05). Contact angle measurements indicated enhanced wettability in IB, PIB, and NiTiB groups (p < 0.05), while the LB group exhibited values comparable to the control (p > 0.05). Mechanical decontamination of implant surfaces utilising rotary brushes can alter implant surface properties.

Mechanical and optical properties of additively manufactured denture base resin in different colors modified with antimicrobial substances: An in vitro study.

Acrylic denture base resins are subject to colonization by oral and nonoral bacteria, contributing to the onset of denture stomatitis. However, how the addition of antimicrobial substances affects the mechanical and optical properties of additively manufactured denture base resin remains unclear. The purpose of this in vitro study was to investigate the surface roughness, color stainability, and flexural strength of antimicrobial-modified, additively manufactured polymethyl methacrylate (PMMA) denture base resin in tooth and gingiva colors. Three antibacterial agents, e-poly-L-lysine+ methacryloyloxyethyl phosphorylcholine (e-MP), silver nanoparticles (AG-P), quaternized ammonium monomer (QA-P) synthesized via the reaction of octyl bromide and DMAEMA, were separately incorporated into tooth- or gingiva-colored 3-dimensionally (3D) printable PMMA specimens, simulating an implant-supported overdenture base or the artificial teeth (n=80). Unaltered specimens served as controls. Autopolymerizing acrylic resin was used to attach titanium matrix housings to gingiva-colored specimens. All specimens underwent coffee thermal cycling (CTC) comprising 10 000 cycles between 5°C and 55°C, and their color coordinates were measured. Surface roughness, color change (ΔE00), and flexural strength were calculated before and after CTC. The results were analyzed and compared by using ANOVA and the Tukey post hoc test (α=.05). All antibacterial agent-incorporated specimens showed lower ΔE00 values than the control (P=.001), with eM-P exhibiting the least color change (P=.001). The control group had the highest post-CTC roughness (Ra) values (P<.001), while all test groups demonstrated higher flexural strength than the control (P=.001). CTC had no significant effect on flexural strength (P>.115). The addition of antimicrobial agents to 3D printable implant overdenture base resin in tooth and gingiva color affected the materials' surface properties, color stainability, and flexural strength. Smoother surface, lower color stainability, and higher flexural strength were observed with the addition of eM-P.

Investigating Fracture Behavior in Titanium Aluminides: Surface Roughness as an Indicator of Fracture Mechanisms in Ti-48Al-2Cr-2Nb Alloys

Titanium aluminides, particularly the Ti-48Al-2Cr-2Nb alloy, have drawn significant attention for their potential in high-temperature aerospace and automotive applications due to their exceptional performances and reduced density compared to nickel-based superalloys. However, their intermetallic nature poses challenges such as limited room-temperature ductility and fracture toughness, limiting their widespread application. Additive manufacturing, specifically Electron Beam Melting (EBM), has emerged as a promising method for producing complex-shaped components of titanium aluminides, overcoming challenges associated with conventional production methods. This work investigates the fracture behavior of Ti-48Al-2Cr-2Nb specimens with different microstructures, including duplex and equiaxed, under tensile and high-cycle fatigue at elevated temperatures. Fracture surfaces were analyzed to distinguish between static and dynamic fracture modes. A novel method, employing confocal microscopy acquisitions, is proposed to correlate surface roughness parameters with the causes of failure, offering new insights into the fracture mechanisms of titanium aluminides. The results reveal significant differences in roughness values between the propagation and fracture zones for all the temperatures and microstructure tested. At 650 °C, the crack propagation zone exhibits lower Sq values than the fracture zone, with the fracture zone showing more pronounced roughness, particularly for the equiaxed microstructure. However, at 760 °C, the difference in Sq values between the propagation and fracture zones becomes more pronounced, with a more substantial increase in Sq values in the fracture zone. These findings contribute to understanding fracture behavior in titanium aluminides and provide a predictive framework for assessing structural integrity based on surface characteristics.

Effect of Staining and External Bleaching on the Color Stability and Surface Roughness of Universal-Shade Resin-Based Composite.

This study evaluated the color stability and surface roughness of two universal-shade compared to two nanohybrid composites after staining and external bleaching with 40% hydrogen peroxide. Two universal shade resin-based composites and two nanohybrid composites were tested. Twenty disc-shaped specimens from each material were fabricated and divided into two subgroups: one group was stained and bleached (staining group) and the other received bleaching treatment only (control group). The staining group was stained with coffee solution for 24h. Subsequently, each sample of all four materials was bleached using an in-office bleaching gel using 40% hydrogen peroxide. Color measurements were performed using a spectrophotometer to obtain the International Commission on Illumination parameters, L*; a*; and b* for each of the following periods: baseline, after bleaching, and two weeks after bleaching for the control group. The staining group was examined at baseline, after staining, after bleaching, and two weeks after bleaching. Surface roughness (Ra) of all the materials after each treatment step were also recorded. The data was statistically analyzed using SPSS 26.0 statistical software. Changes were considered statistically significant at P = 0.05. Descriptive statistics (means and standard deviations) were used to describe color measurements and surface-roughness values. Two-analysis of variance and one-way analysis of variance were used to compare the mean values of surface roughness, L*a*b*and ΔE00 values. Statistically significant differences and clinically acceptable ΔE00 were observed between all materials during the different stages in color measurements, whereas the surface roughness was significantly different for each study material and treatment mode. Staining with coffee solution and external bleaching produced acceptable color changes for all materials tested. Staining and bleaching increased the surface roughness values of the tested resin-based composites.

Surface roughness of composite resins subjected to brushing with whitening toothpastes: an in vitro study.

The emergence of toothpastes containing different abrasive and whitening substances has been a constant concern among dental professionals. The aim of the present study was to perform an in vitro assessment of the surface topography of nanoparticle composite resins subjected to simulated brushing with dentifrices. Test samples were prepared with Filtek Universal (3M ESPE), Filtek Bulkfill (3M ESPE) and Z350 (3M ESPE), with 24 samples per resin. A testing machine was used to simulate brushing with the dentifrices Colgate Total 12, Oral B 100% and Oral B Gengiva Detox Gentle Whitening (8 samples per group). The constant speed of the machine was 250 cycles per minute, and 20.000 cycles were carried out, which corresponds to 24 months (1 hour and 20 minutes). Roughness features and qualitative surface topography were investigated. Statistical analysis involved the Kruskal-Wallis, Wilcoxon and Mann-Whitney tests. A significant increase in surface roughness was found for all the resins (p < 0.05). However, no significant difference was found among the resins in terms of final roughness values (p = 0.690). In contrast, a significant difference among dentifrices was found with respect to roughness measurements (p < 0.001). The qualitative analysis revealed an increase in surface roughness in all the samples and differences in the abrasive potential of the dentifrices. In conclusion, brushing with dentifrices increases the surface roughness parameters of composite resin restorations. Moreover, the differences in the abrasive effects of the dentifrices indicate a need for further studies to establish efficacy and safety criteria.

Bilateral submerged abrasive waterjet peening improved high-temperature fatigue strength of titanium alloy thin-walled simplified blades

Waterjet peening has exhibited excellent performance in improving the surface integrity and fatigue life of metal components. This paper proposes a novel and efficient thin-walled simplified-blade-surface full-coverage strengthening method, namely the bilateral submerged abrasive waterjet peening process (BSA-WJP), to improve the surface integrity and fatigue strength of simplified aeroengine blades. First, the surface integrity of simplified titanium alloy TA19 blades treated with BSA-WJP at different abrasive flow rates (100, 175, and 250 g/min) was investigated. The results revealed that the lowest surface roughness value of Ra = 0.329 μm was obtained. Compressive residual stress (CRS) layers of 111–128 μm with a maximum CRS of 738 MPa were introduced to the simplified blade surface. Plastic deformation layers of 15–32 μm were formed on the simplified blade surface after BSA-WJP treatment. The microstructure of the BSA-WJP-treated simplified blade was further examined using transmission electron microscopy. It was found that ultrafine grains with an average size of 107 nm and dense dislocations were induced on the topmost surface and subsurface. Finally, the high-cycle vibration fatigue performance of the simplified TA19 blade at 450 °C was verified. The result revealed that a 13.6 % increase in the high-temperature fatigue limit of the simplified TA19 blade was achieved after BSA-WJP treatment. The fracture morphology revealed that the considerable CRS, grain refinement layer, and optimized surface morphology played significant roles in inhibiting the initiation and propagation of cracks. This study provides an effective method for improving the fatigue strength of titanium alloy thin-walled blades and has promising engineering application prospects.

The structural, optical, topographical, and H2 sensing characteristics of a Zn-doped Fe2O3 thin layer deposited via DC & RF magnetron co-sputtering method

In this study, a Zn-doped iron oxide layer was deposited onto a microscope slide using the magnetron co-sputtering technique with direct current (DC) and radio frequency (RF) sources. We comprehensively characterized the resulting Zn-doped Fe2O3 thin layer, employing techniques such as XRD, Raman spectroscopy, UV–VIS spectrophotometry, SEM, EDX, & AFM. XRD examination showed the nanocrystalline structure in the thin layer under investigation. Based on recorded absorption data, the band gap energy value calculation resulted in a value of 2.23 eV for the thin film. Raman spectroscopy identified peaks possessing Raman shifts from 100 to 1400 cm−1. SEM investigation illustrated a consistently uniform thin film surface characteristic throughout the substrate. Additionally, the AFM study disclosed a small RMS roughness value, indicative of an unrough surface for the Zn: Fe2O3 thin layer. The Fe2O3 thin film doped with Zn employing a 30 W DC voltage demonstrated effective hydrogen sensing capability at 300 °C, achieving notable response and recovery time. This work presents a novel application of Zn-doped Fe2O3 thin films as highly sensitive and stable hydrogen sensors, tailored for high-temperature environments. The unique combination of nanocrystalline structure and Zn doping optimizes the material’s electronic properties, enhancing its responsiveness to hydrogen gas. This approach offers a scalable, cost-effective pathway for developing advanced sensor technologies suited to environmental monitoring, industrial safety, and hazardous gas detection, making it a valuable addition to the field of gas-sensing materials.

Surface Roughness and Color Stability of Conventional and Bulk-Fill Resin Composite with S-PRG Fillers After Coffee Exposure: An in-vitro Study.

This study aimed to evaluate the in vitro effects of coffee exposure on the color and roughness of conventional and bulk-fill resin composites, with and without surface pre-reacted glass-ionomer (S-PRG) filler. Forty-eight cylindrical samples (Ø6 mm × 2 mm) were prepared and categorized as follows (n = 12 per group): conventional nano-hybrid (Tetric N-Ceram, Ivoclar); nano-hybrid with S-PRG filler (Beautifil II, Shofu); bulk-fill (Tetric N-Ceram Bulk Fill, Ivoclar); and bulk-fill with S-PRG filler (Beautifil Bulk Restorative, Shofu). The samples were assessed for surface roughness (Ra, μm), color coordinates (CIE Lab), and overall color change (ΔEab, ΔE00). Measurements were taken at baseline and after 7 days of coffee immersion (pH = 4.95). Data were analyzed using generalized linear models, Kruskal-Wallis, Dunn, and paired Wilcoxon tests (α = 0.05). After the coffee exposure, all resin composites exhibited a significant decrease in L* (towards black), an increase in a* (towards red), an increase in b* (towards yellow), and a higher Vita color score (p < 0.05). Tetric N-Ceram demonstrated the lowest roughness values post-exposure; however, a significant increase in roughness over time was observed only for Tetric N-Ceram Bulk Fill (p < 0.05). For ΔEab, Beautifil Bulk Restorative and Tetric N-Ceram showed higher values compared to Beautifil II. For ΔE00, a significant difference was noted between Beautifil Bulk Restorative and Beautifil II (p < 0.05). Resin composites with S-PRG fillers exhibited similar pigmentation dynamics to conventional composite but showed greater surface roughness after exposure to coffee. Considering the S-PRG materials, the bulk-fill version is more susceptible to staining.

Experimental investigation of CF8 stainless steel impeller quality using PLA-based fused deposition modeling-assisted investment casting

Abstract The conventional Investment Casting (IC) process is extensively used for manufacturing parts with intricate shapes and complex geometries. However, its drawbacks include long cycle times and costly tooling, making it ideal for mass production but inefficient for frequent design changes, small batch production, or customized products. To address these challenges, a novel hybrid method known as Fused Deposition Modeling Assisted Investment Casting (FDMAIC) has been developed. In FDMAIC, the wax pattern is replaced by an FDM-printed pattern, while all other steps follow the conventional IC process. In this study, a semi-open impeller for a centrifugal pump was produced using FDMAIC, with Polylactic Acid (PLA) as the pattern material and CF8 for casting. Dimensional accuracy and surface roughness, key indicators of quality, were evaluated at both the printing and casting stages. Critical dimensions such as outer and inner diameters, shroud and blade thicknesses, and total height were measured, along with surface roughness at the shroud and blade surfaces. In the final cast, maximum dimensional deviation was observed in Outer diameter(−2.408 mm), and minimum dimensional deviation was observed in total height(−0.169 mm). The surface roughness values obtained at the shroud and blade surface of the final cast were 4.64 μm 6.67 μm, respectively. Microstructure and hardness testing were also performed on the FDMAIC impeller to validate the process. The results provide detailed insights into the feasibility of FDMAIC and suggest areas for further improvement.

Fundamental investigations on temperature development in ultra-precision turning

Ultra-precision machining represents a key technology for manufacturing optical components in medical, aerospace and automotive industry. Dedicated single crystal diamond tools enable the production of innovative optical surfaces and components with high dimensional accuracies and low surface roughness values in a wide range of airborne sensing and imaging applications concerning space telescopes, fast steering mirrors, laser communication and high-energy laser systems. Despite the high mechanical hardness of single crystal diamonds, temperature-induced wear of the diamond tools occurs during the process. In order to increase the economic efficiency of ultra-precision turning, the characterisation and interpretation of cutting temperatures are of utmost importance. According to the state-of-the-art, there are no precise methods for online temperature monitoring during the process at the cutting edge with regard to the requirements for resolution accuracy, response time and accessibility to the cutting edge. For this purpose, a dedicated cutting edge temperature measurement system based on ion-implanted boron-doped single crystal diamonds as a highly sensitive temperature sensor for ultra-precision turning was developed. To enable highly sensitive temperature measurements, ion implantation was used for partial and specific boron doping close to the cutting edge of single crystal diamond tools. Within the investigations, a resolution accuracy of 0.29 °C ≤ aR ≤ 0.39 °C could be proven for the developed cutting edge temperature measurement system. In addition, a total measurement uncertainty of uM = 0.098 °C was determined for the sensor accuracy aS in the investigated process area. For a rake angle range of 0° ≤ γ0 ≤ −30°, reaction times of 420 ms ≤ tR ≤ 440 ms were further determined. Using the developed cutting edge temperature measurement system enables a holistic view of the temperature development during ultra-precision machining, whereby a correlation between the measured cutting temperatures and the chip formation mechanisms depending on the applied process parameters could be identified. Within the investigations, the highest measured temperatures of ϑM = 50.18 °C and simulated maximum temperatures of ϑS,max = 183.12 °C were determined at a cutting speed of vc = 350 m/min, a cutting depth of ap = 35 µm as well as a feed of f = 35 µm using a rake angle of γ0 = −30°. The most uniform chips with the smoothest surfaces were identified within the chip analysis using a cutting speed of vc = 50 m/min, a cutting depth of ap = 5 µm and a feed of f = 35 µm with a measured temperature of ϑM = 21.30 °C and a simulated temperature of ϑS = 38.47 °C in the examined finishing area. According to the results, it was also shown that the cutting edge temperature measurement system with ion-implanted diamonds can be used for both electrically conductive and non-conductive materials. This provides the fundamentals for further research works to identify the complex temperature-induced wear behaviour of single crystal diamonds in ultra-precision turning and serves as the basis for self-optimising and self-learning ultra-precision machine tools.

On the surface roughness of 316L stainless steel fabricated using L-PBF additive manufacturing

Additive manufacturing (AM) offers numerous advantages over traditional fabrication methods such as manufacturing complex parts. However, a significant limitation lies in the restricted surface quality, hindering its widespread use. While parts produced through conventional manufacturing techniques such as milling and grinding typically have an average roughness (Ra) value of less than 1–2 μm, those manufactured using laser powder bed fusion (LPBF) AM usually fall within the range of 10 to 30 μm. Surface roughness plays a critical role in various applications, as certain uses necessitate superior surface quality to prevent premature failure due to surface-induced cracking. Subpar surface quality not only compromises the strength, wear resistance, and corrosion resistance of parts but also impacts the precision of the fabricated components. Therefore, it is imperative to optimize the fabrication process and enhance the surface quality of metal parts. Moreover, the surface quality of each layer dictates the bonding strength between adjacent layers and process stability, as a high-quality preceding surface is essential for ensuring the integrity of subsequent layers. Consequently, surface roughness significantly influences process stability and the properties of metal parts produced through LPBF. This work aims at evaluating surface roughness of as printed 316L stainless steel parts made using LPBF AM process and their effects on tensile properties of the produced samples. Microscopic analyses are done to evaluate the roughness (including Ra, Rq, and Sa parameters) at different locations to evaluate the effects of different printing parameters on their size distributions. In addition, the macro-mechanical behaviour of the as printed samples is compared with the ones with polished surface.

Investigation of the Effect of Cutting-Edge Rounding on Surface Quality in Milling of Al 7075 and Al 6082 Alloys

Al 7075 and Al 6082 alloys are alloys that are widely used in many sectors, especially aviation and automotive. During their processing along with the widespread use of those alloys, significant machinability problems such as low surface quality due to chip accumulation (Built Up Edge-BUE) on the cutting edge are observed. In this study, the effect of cutting-edge corner rounding and machining parameters on surface roughness in milling of Al 7075 and Al 6082 alloys were experimentally investigated. To determine the effect of cutting-edge rounding, two different corner rounding values (5.5-6 µm and 7-9 µm) were applied and compared with standard/coated and standard/uncoated tools in terms of machining performance. In the experimental studies, cutting parameters were determined as two different cutting speeds (300 m/min, 400 m/min) and two different feed rates (0.085 mm/tooth, 0.11 mm/tooth). With each tool, peripheral milling was performed on four sides of the prismatic test specimens under dry machining conditions. Taguchi L8 orthogonal array experimental design was used as the experimental design. Analysis of variance (ANOVA) was performed to evaluate the effects of cutting parameters on surface roughness and the reliability of all results was above 85%. The results of the analysis of variance revealed that the alloy type was more effective on the surface roughness. In the surface roughness measurements, the best surface roughness values (Ra=0.14 µm) were obtained in the experiments performed with a standard/coated cutting tool using a cutting speed of 300 m/min and a feed rate of 0.11 mm/tooth.

The differences in surface roughness and hardness of glass ionomers cement coated with vaseline and cocoa butter after immersion in UHT milk

Background: Dental caries affects 513.8 million children globally, and glass ionomer cement (GIC) is a common treatment due to its fluoride release. However, GIC is moisture-sensitive and prone to solubility during maturation. UHT milk, often consumed by children, disrupts ionic bonds on GIC surfaces affecting roughness and hardness. Increased surface roughness leads to plaque accumulation, while decreased surface hardness ensures compressive strength and abrasion resistance. Coating agents like vaseline and cocoa butter help preserve GIC properties by maintaining roughness and hardness. Purpose: To analyze differences in surface roughness and hardness values of GIC treated with vaseline, cocoa butter, and without coating after being immersed in UHT milk for 7 days. Methods: The experimental study used a post-test control group design with three groups of six specimens each, immersed in UHT milk for seven days. Groups included GIC without coating, coated with vaseline, and cocoa butter. The test results were then measured using a surface roughness tester and Vickers hardness tester and analyzed using the ANOVA. Results: GIC coating with vaseline has the lowest value of surface roughness and highest surface hardness, followed by GIC coating with cocoa butter and without coating. However, the three groups did not have significant differences in statistical data analysis. Conclusion: There is no difference in the surface roughness and hardness values of GIC without coating, coated with vaseline, or cocoa butter after being immersed in UHT milk for 7 days.

Design and Characterization of Novel Polymeric Hydrogels with Protein Carriers for Biomedical Use.

Hydrogels are three-dimensional polymeric matrices capable of absorbing significant amounts of water or biological fluids, making them promising candidates for biomedical applications such as drug delivery and wound healing. In this study, novel hydrogels were synthesized using a photopolymerization method and modified with cisplatin-loaded protein carriers, as well as natural extracts of nettle (Urtica dioica) and chamomile (Matricaria chamomilla L.). The basic components of the hydrogel were polyvinylpyrrolidone and polyvinyl alcohol, while polyethylene glycol diacrylate was used as a crosslinking agent and 2-methyl-2-hydroxypropiophenone as a photoinitiator. The hydrogels demonstrated high swelling capacities, with values up to 4.5 g/g in distilled water, and lower absorption in Ringer's solution and simulated body fluid (SBF), influenced by ionic interactions. Wettability measurements indicated water contact angles between 51° and 59°, suggesting balanced hydrophilic properties conducive to biomedical applications. Surface roughness analyses revealed that roughness values decreased after incubation, with Ra values ranging from 6.73 µm before incubation to 5.94 µm after incubation for samples with the highest protein content. Incubation studies confirmed the stability of the hydrogel matrix, with no significant structural degradation observed over 20 days. However, hydrogels containing 2.0 mL of protein suspension exhibited structural damage and were excluded from further testing. The synthesized hydrogels show potential for application as carriers in localized drug delivery systems, offering a platform for future development in areas such as targeted therapy for skin cancer or other localized treatments.

Influence of Different Spot Pattern Lasers on Cleaning Effect of TC4 Titanium Alloy.

This study employed different spot pattern lasers to clean the oxide film on the surface of a TC4 titanium alloy. The variation in temperature field and ablation depth during the laser cleaning process was simulated by establishing a finite element model. The effects of various laser processing parameters on the micromorphology, elemental composition, and surface roughness of the TC4 titanium alloy were analyzed. The results show that as the laser energy density increases, both the temperature field and ablation depth increase as well. Under optimal laser processing parameters, the laser energy density is 5.27 J/cm2, with a repetition frequency of 300 kHz and a scanning speed of 6000 mm/s. A comparison of the cleaning effects of Gaussian pulse lasers and Flat-top pulse lasers reveals that the Gaussian pulse laser causes less damage to the TC4 titanium alloy, resulting in lower oxygen content and roughness values after cleaning compared to Flat-top pulse laser cleaning.