Surface Roughness Of Specimens Research Articles

Benzyldimethyldodecyl Ammonium Chloride-Doped Denture-Based Resin: Impact on Strength, Surface Properties, Antifungal Activities, and In Silico Molecular Docking Analysis.

Candida albicans (C. albicans) adhering to denture-based resins (DBRs) is a known cause of denture stomatitis. A new approach to prevent denture stomatitis is to include antimicrobial substances within DBRs. Here, we examined the mechanical performance and antifungal properties of DBRs containing benzyldimethyldodecyl ammonium chloride (C12BDMA-Cl) as an antimicrobial compound. C12BDMA-Cl is a quaternary ammonium compound, and its antifungal properties have never been investigated when combined with dental acrylic resin. Therefore, we modified a commercially available heat-polymerized acrylic DBR to contain 3 and 5 wt.% of C12BDMA-Cl. Unmodified DBR was used as a control group. Specimens were prepared using the conventional heat processing method. The specimen's flexural strength, elastic modulus, microhardness, and surface roughness were evaluated. C. albicans biofilm was grown on the specimens and assessed via colony-forming units (CFUs) and scanning electron microscopy (SEM). In silico molecular docking was applied to predict the potential C12BDMA-Cl inhibition activity as an antifungal drug. The 3% C12BDMA-Cl DBR demonstrated antifungal activities without a deterioration effect on the mechanical performance. SEM images indicated fewer colonies in DBR containing C12BDMA-Cl, which can be a potential approach to managing denture stomatitis. In conclusion, C12BDMA-Cl is a promising antifungal agent for preventing and treating denture stomatitis.

Study on the deep deoxidation mechanism of titanium powder using Y/YOCl/YCl3 and Y/Y2O3 systems

Low-oxygen high-purity titanium (oxygen concentration ≤ 500 ppm) is a critical material for advanced semiconductor and biomedical applications. Current deoxidation methods limit oxygen concentration in titanium to approximately 1000–2000 ppm, failing to meet the demand for ultra-low oxygen levels in high-performance materials. This study investigated the preparation mechanism and conditions for low-oxygen high-purity titanium utilizing a molten salt thermochemical method, employing Y as the deoxidant with a theoretical deoxidation limit below 10 ppm. We experimentally explored the deoxidation mechanisms of titanium using Y/YOCl/YCl3 and Y/Y2O3 systems, successfully reducing the oxygen concentration in titanium to 200 ppm, and proving that the Y/YOCl/YCl3 system is more efficient than the Y/Y2O3 system. Additionally, the titanium samples were analyzed using SEM-EDS, XRD, XPS, and 3D surface profilometry before and after deoxidation. These analyses examined the impact of the deoxidation process using Y on the crystal structure, oxide film, and surface roughness of titanium specimens, which are useful for understanding the deoxidation mechanism. During the sintering process of titanium powder attached to Y, the deoxidation process will produce YOCl or Y2O3. The formation of these deoxidation products leads to local oxygen diffusion, and the crystals of YOCl or Y2O3 are gathered at grain boundaries, which will resolve during the subsequent acid etching process, thus reducing the oxidation concentration of the titanium. The above results provide further theoretical guidance and technical support for the production of ultra-high-purity titanium powder.

An experimental investigation of abrasive jet machining parameters for optimized surface finish of mild steel components

Abrasive jet machining is one of the unconventional machining processes that are initiated for alternations of surface characteristics of ductile materials, like mild steel, due to the entrainment of high-velocity abrasive particles. The present experimental investigation deals with the major process parameters of the AJM process, namely air pressure, standoff distance, and time of machining, on the average surface roughness (Ra) of mild steel specimens. Experiments were conducted on the self-developed AJM setup using aluminum oxide abrasive particles of an average size of 50 µm. The pressure of air is changed in three levels, 6, 7, and 8 bars. The standoff distance is taken as 2 mm constant for all the cases. The surface roughness was measured at machining times of 20, 40, and 45 seconds. The presence of the increase of air pressure from 6 to 8 bars applied for all the machining time showed an increasing influence on roughness, although always significant in Ra. For 8 bars of pressure and 45 s of machining, the minimum resulted in 1.39 µm, compared with 3.47-4.02 µm. The rate of decrease in surface roughness is sharp with increasing machining time from 20 to 40 seconds but marginal beyond that. An optimal machining time of 40–45 seconds was identified to obtain a minimum Ra. Capability of AJM as an effective technique to enhance the surface finish of mild steel components, and practical insight of this study is very useful toward optimization of process parameters for attaining the targeted surface quality. The results obtained may assist in expanding the industrial application of AJM toward the finishing of ductile materials in various manufacturing fields.

Optimal Hydrofluoric Acid Etching Duration and Impact of Silane/Adhesive on Profilometric Properties and Bonding to Lithium Disilicate Glass Ceramics.

This study aimed to assess the surface roughness, surface free energy (SFE), and shear bond strength (SBS) on a lithium disilicate glass-ceramic surface following varying etching protocols (time variation) and application of silane either with or without adhesive material. Lithium disilicate glassceramic (LDGC) computer-aided design and computer-aided manufacture (CAD/CAM) blocks were cut using a slow-speed cutting mechanism. CAD/CAM blocks were then evaluated for surface roughness, 6 groups (n=20); SFE,12 groups (n=5); and SBS, 10 groups (n=10). The cut CAD/CAM blocks were randomly allocated to 28 groups. Groups were based on the following: 30 or 90 seconds of etching with 9% hydrofluoric acid (HF); application or absence of silane coupling agent (Sil); and application or absence of adhesive (Adh).The control group (Cont) had untreated surfaces. Unetched surfaces were surveyed with only silane (Sil), only adhesive (Adh), or silane+adhesive (SilAdh). Further etched groups were HF30 with HF for 30 seconds, HF30-Sil, HF30-Adh, and HF30-SilAdh. Alternative 90-second etching times produced similar groups: HF90, HF90-Sil, HF90-Adh, and HF90-SilAdh. A digital profilometer was used to assess the surface roughness of specimens, and two readings were recorded. Sessile drop analysis was used to examine SFE specimens, and the OWRK model was modified to measure liquid surface tension. A universal testing machine (UltraTester, Ultradent Products, Inc, South Jordan, UT, USA) was utilized for the SBS test, with the crosshead speed set at 0.5 mm/min until failure. Representative treated specimens from each group were submitted to surface morphological evaluation and chemical analysis using scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDXS) (n=3). After data collection, evaluation using one- or two-way analysis of variance and the post-hoc Tukey test (α=5%) was conducted. A longer etching time of 90 seconds produced a rougher surface. After the 90-second etching process, SFE displayed the greatest values; nevertheless, the use of silane did not affect SFE. For every group examined, the application of silane followed by adhesive resulted in an increase in SBS and more stable bonding over time. SEM/EDXS showed that etching times did affect the amount of cerium on the surface and altered surface morphology. Higher and more consistent bond strengths have been observed with longer etching periods. Silane and adhesive application on the ceramic surface showed stronger and enhanced bond strength, specifically when longer etching times were employed.

Investigation of surface finish and fatigue life of laser Powder Bed fused Ti-6Al-4V

In this fact-pacing world of technological advancement, the rise of additive manufacturing (AM) has found immense applications of metallic alloys such as Ti6Al4V to manufacture key components in automotive, aerospace and healthcare sectors. However, fatigue characteristics of such additively manufactured metal alloys is noticeably weak, and as such requires post-processing. In this study, AM Ti6Al4V manufactured by Laser Powder Bed Fusion (L-PBF) was treated by Hydrodynamic Cavitation Abrasive Finishing (HCAF) and Laser Cavitation Peening (LCP) to observe the improvement in surface roughness as well as fatigue performance. Our investigations revealed a substantial improvement in surface quality post-HCAF processing. Notably, the surface roughness of AM Ti6Al4V specimens showed a significant reduction of about 91.2 %, post surface treatment. However, Laser Cavitation Peening (LCP) treated sample demonstrates a significantly enhanced fatigue strength of 393 ± 22 MPa at 107, which was 1.75 times better than that of as-built one, i.e., 224 ± 16 MPa. This difference can be attributed to the distinct surface modification mechanisms of each technique. LCP, utilizing laser-induced shock waves, likely induces large compressive residual stresses, leading to better fatigue resistance.

Hole quality geometrical measurement and surface roughness for α-Phase titanium alloy (α-Ti-6Al-4V) materials by using L-PBF (laser powder bed fusion) orthopedic implant application

This study examines the quality of circular-hole 3D-printed objects using laser powder bed fusion (L-PBF) on Ti-6Al-4V titanium alloy that typically used for orthopedic implants. Meanwhile measuring surface roughness and hole dimension deviations in AM specimens is very challenging. Thus, the specimens were printed with varying process parameters, followed by an L9 orthogonal array experiment, where parameters included laser power (LP) at 175, 185, and 195 W; scanning speed (SS) at 600, 900, and 1200 mm/s; and hatch distance (HD) at 70, 90, and 110 µm. Thus the, minimum surface roughness values are Ra 2.4 µm for the top surface and Ra 16.06 µm for the inside hole curve. Whereas the smallest hole deviations are 0.1102 mm for external and 0.2094 mm for internal diameters. Therefore, this analysis include FESEM, EDX, XRD, profilometry and stereomicroscopy. Where the best settings are LP 195 W, SS 900 mm/s, and HD 70 µm, producing well-fused, uniform α-phase Ti-6Al-4V specimens that are suitable for biomedical applications.

Water Sorption and Solubility of Highly Aesthetic Single-Shade Nano-Hybrid Resin Composites.

Background A single-shade resin composite is a new type of resin composite that was introduced in 2019. There is not much data regarding the water sorption (Wsp) and water solubility (Wsl) of this type of resin composite. Therefore, this study aimed to investigate Wsp and Wsl and their effects on the surface roughness of a single-shade nano-hybrid resin composite in comparison with a conventional nano-hybrid resin composite in accordance with ISO 4049:2019 (Dentistry - Polymer-based Restorative Materials). Material and methods An in vitro study was performed to investigate the Wsp and Wsl of a single-shade supra-nano-hybrid composite (Omnichroma) and a conventional nano-hybrid composite (Filtek™ Z250 XT) in accordance with ISO 4049:2019. Five disks were prepared of each material with dimensions of 15 ± 1 mm in diameter and 1 ± 0.1 mm in thickness, as per ISO 4049:2019. The results were calculated according to the ISO equations for Wsp and Wsl in µg/mm3. Atomic force microscopy (AFM) was used to analyze the surface roughness (Ra) of test specimens. Results The findings showed that the values of Wsl and Wsp of both materials are comparable and revealed no statistically significant difference (P > 0.05). The AFM images showed a higher Ra post-solubility testing, and the statistical analysis indicated a significant difference for both materials. Conclusions The study concluded that the single-shade resin composite (Omnichroma) and the conventional nano-hybrid composite (Filtek™ Z250 XT) are following the requirements of ISO 4049:2019. The AFM analysis indicated that resin composite surfaces are significantly affected when exposed to water for a prolonged period of time. However, the Ra variations of Filtek™ Z250 XT were higher than Omnichroma specimens. These results indicate that resin composite surfaces can be significantly impacted by prolonged water exposure. This knowledge is critical for enhancing the long-term clinical performance and durability of these dental restorative materials.

Effect Of Air-Abrasion And Er:Yag Laser On The Bond Strength Between The Metal Housing Of An Overdenture Attachment System And The Hard Relining Material

Objective. This study investigated the effect of air-abrasion and erbium:yttrium-aluminum-garnet (Er:YAG) laser treatments on push-out bond strength (PBS) between hard relining material and metal housing of an overdenture attachment system. Material and Methods. A total of 36 metal housings were randomly divided into 3 subgroups according to surface pretreatments (n=12): Control (no surface treatment; C), air-abrasion (A), and Er:YAG laser (L). Surface roughness (Ra) of specimens was determined using a profilometer. One additional specimen per group was evaluated by scanning electron microscopy (SEM). The hard relining material was bonded to metal housings, and a PBS test was performed using a universal testing machine. Data were statistically analyzed using 1-way analysis of variance (ANOVA), Tukey’s honestly significant difference (HSD), and Tamhane’s T2 tests (α=.05). Results. C and L groups showed the lowest and highest Ra values, respectively. The mean Ra of the A group was statistically different from the mean values of the C and L groups (P<.001). The L group showed higher PBS values than the C group (P<.05), whereas the A group exhibited statistically similar PBS values to both C and L groups (P>.05). Conclusions. Air-abrasion did not significantly increase the bond strength between the metal housing and hard relining material. Er:YAG laser irradiation noticeably improved the PBS but caused surface microcracks.

EXPERIMENTAL INVESTIGATION ON ONE-WAY ABRASIVE FLOW MACHINING ON HOT WORK STEEL

Abrasive flow machining (AFM) is a process where a semi-solid abrasive-laden media is forced to flow through the internal passages of a workpiece under pressure. In high-resolution work, increased accuracy and faster smooth surface polishing work with the developed motorized AFM prototype. This research presents the effect of the clearance of specimen tools for surface roughness (Ra) of SKD 61 (AISI H13) hot work steel related to AFM. This research experimented with half-spherical specimens. AFM experiments are performed to identify the improved surface roughness when applied to the polishing specimens. Specimens were prepared by being turned, hardened, and polished with sandpaper from number P180 to P1200 and measured with an original value of Ra compared with the final value of Ra at the end of the process. The experimental prototype uses a unidirectional motor drive system different from previously developed machines. The process parameters are as follows: a pressure (p) of 1, 2, and 3 bar, cycle time (t) of 10, 15, and 20 min., an abrasive particle size (Al2O3) of 5.0 μm in Silicon Oil (50 % concentration by weight), hardness of specimens 45±2 HRC, etc. The experimental results show that under these conditions, the average surface roughness of specimens was decreased from an original value of Ra 0.057 to 0.042 μm. The greatest response surface (RSM) was obtained at a pressure of 3 bar and a time of 20 minutes. The result allows for better precision control and further development in industrial applications.

Surface roughness and optical characteristics evaluations after chairside adjustment of different zirconia types.

Limited evidence is available for the effect of chairside adjustment using rotary cutting instruments on the surface roughness and optical properties of different zirconia types. To evaluate the effect of simulated adjustments on surface roughness and optical properties of different zirconia types. Three Partially Stabilized Zirconia (PSZ) types based on mole percent yttria (Y) concentration from the same manufacturer (Katana; Kuraray) were used: 3Y-PSZ, 4Y-PSZ, and 5Y-PSZ. Thirty disk-shaped specimens (Ø14 × 1.2 mm) from different zirconia types (N = 90) were prepared. Specimens were either left without adjustment (NA), adjusted with Dialite ZR finishing and polishing system (Brasseler) (APol), or adjusted with course diamond instruments only (ADia). The specimens were distributed into 9 groups (n = 10): Group 3Y-PSZ/NA, Group 3Y-PSZ/APol, Group 3Y-PSZ/ADia, Group 4Y-PSZ/NA, Group 4Y-PSZ/APol, Group 4Y-PSZ/ADia, Group 5Y-PSZ/NA, Group 5Y-PSZ/APol, and Group 5Y-PSZ/ADia. The surface roughness of specimen was analyzed using an Atomic Force Microscope (AFM) (Bruker's Dimension Icon, Bruker) and Root Means Square (RMS) were recorded (nm). Surface Gloss (SG), Translucency Parameter (TP), and Contrast Ratio (CR) values of all groups were recorded using an integrating sphere spectrophotometer. Statistical analysis was performed using analysis of variance (ANOVA) and Tukey's multiple comparison tests for pairwise comparisons at p < 0.05 and 95% confidence interval. APol had no effect on the surface roughness (p = 0.88) while ADia had a significant negative effect (p < 0.05) despite the type of zirconia. Out of the three testes optical properties, only SG was negatively affected by ADia for all types of zirconia (p < 0.05). The two adjustment types did not affect the TP of all the tested zirconia (p = 0.91). The CR was not affected by the tested adjustments for all zirconia types (p = 0.726). Proper zirconia adjustment following a sequence of burs and polishers can maintain acceptable roughness and optical properties. Adjustment of zirconia with rough diamond can lead to deleterious effects and should be avoided. Chairside adjustment of zirconia could lead to rougher surface and unpredictable changes of surface gloss. Therefore, zirconia adjustment should be minimized to the greatest extent possible and a proper protocol should be followed if had to be done.

Improvement of fatigue life of Ti-6Al-4V alloy treated by double-sided symmetric oblique laser shock peening

To improve the anti-foreign object damage (FOD) ability of Ti-6Al-4V alloy blisk blades, a blade simulation specimen was designed and subjected to double-sided symmetrical oblique laser shock peening (DSOLSP) treatment. Surface roughness, residual stress distribution, and microstructural evolution of simulated specimens of Ti-6Al-4V alloy without and with DSOLSP were investigated, and the strengthening effect was evaluated by flexural fatigue test. The results showed that after DSOLSP treatment, surface roughness of simulated specimens was reduced from Ra0.97 µm to Ra0.6 µm. DSOLSP treatment generated a compressive residual stress (CRS) field along the entire thickness direction of the simulated specimen. Nanostructures with a depth of ∼500 nm was observed at topmost surface layer, and the average size of the nanograins was about 35.2 nm. Compared with the base material, the flexural average fatigue life of the simulated specimen was increased by 8.45 times. Moreover, mathematical statistical analysis confirms that DSOLSP has a significant effect on the fatigue life of simulated samples. The development of CRS fields throughout the entire thickness direction, the grain refinement on the surface, and the reduction of surface roughness are primarily responsible for the enhancement of the flexural fatigue life of the DSOLSP simulated specimen.

Effect of Force and Heat Coupling on Machined Surface Integrity and Fatigue Performance of Superalloy GH4169 Specimens

GH4169 is one of the key materials used to manufacture high-temperature load-bearing parts for aero-engines, and the surface integrity of these parts in service conditions significantly affects their high-temperature fatigue performance. Under a coupling effect of high temperature and alternating load, the evolution process of the machined surface integrity index of superalloy GH4169 specimens was studied, and fatigue performance tests at 20 °C, 450 °C, and 650 °C were carried out to analyze the primary factors affecting the high-temperature fatigue performance of specimens. The results indicated that the surface roughness of specimens remained essentially unchanged. However, the value of surface residual stress decreased significantly, with a release of more than 60% at the highest temperature. At 650 °C, the surface microhardness increased, while the degree of surface plastic deformation decreased under alternating loads. Simultaneously, when the surface roughness was less than Ra 0.4 μm, surface microhardness was the main factor affecting the high-temperature fatigue performance of specimens. The influence of surface microhardness on low-cycle fatigue performance was not consistent with that on high-cycle fatigue performance. The latter increased monotonically, whereas the former initially increased and then decreased with increasing surface microhardness.

The effect of biomimetic laser surface treatment on the wear performance of high manganese steel

High manganese steel finds widespread applications in diverse friction and wear environments. The poor wear resistance of high manganese steel at low stress levels has prompted researchers globally to focus on studying its wear performance. Drawing inspiration from the protective features of pangolin scales, this study employed a pulsed radiation mode CO2 laser to conduct biomimetic laser surface treatment (BLST) on Mn13 high manganese steel. The BLST generated a biomimetic surface morphology consisting of tiny scales on the high manganese steel specimens. Subsequently, the biomimetic laser surface-treated (BLSTed) specimens underwent tests for surface morphology, microstructure, microhardness, and surface roughness. These tests employed metallographic microscopy, scanning electron microscopy, a microhardness tester, and a surface profilometer, respectively. A ring block friction and wear testing machine was utilized to evaluate the wear performance of the BLSTed specimens. Changes in laser power, laser frequency, and laser scanning velocity were found to alter the surface morphology of BLSTed specimens. The experimental results revealed that the microstructure of the BLSTed specimen surface comprised needle-like martensite. The increment in surface hardness and surface roughness of BLSTed specimens contributed to an elevation in their average friction coefficient. Furthermore, the surface hardness and wear performance of BLSTed specimens exhibited varying degrees of improvement with the increase in laser power, laser frequency, and laser scanning velocity. The tiny biomimetic scales, created through BLST, provided protection to high manganese steel akin to the protective scales on the body of pangolins. Finally, the study unveiled the wear resistance mechanism of BLSTed specimens.

Effect of propolis on the mechanophysical properties of addition silicon dental impression material

Background Dental impressions should be disinfected to stop the transmission of germs among dental workers since they provide a risk of diseases. The aim of this study was to examine the effects of two disinfectants (16 mg/ml propolis and 5.25% sodium hypochlorite) on the detail reproduction, linear dimensional change, compatibility with gypsum products, wettability, and surface roughness of addition silicon material. Methods Ninety specimens were created using Addition silicon impression material, and they were then divided into three groups at random. Ten specimens from each test group were used in each test. Utilizing apparatus made in accordance with ISO 4823:2015, detail reproduction, linear dimensional change, and compatibility with gypsum products are assessed. A digital Profilometer was uutilized to evaluate surface roughness, and a Goniometer was utilized to evaluate wettability by taking the contact angle. Before testing, the specimens were immersed for 10 minutes each in two disinfection solutions: 16 mg/ml propolis and 5.25% NaOCL. The control group received no disinfection. One-way ANOVA tests and the Kruskal-Wallis test, which was statistically significant at a level of p 0.05, were used to examine the data. Results Comparing the linear dimensional change, surface roughness, and wettability of Addition silicon specimens immersed in 16 mg/ml propolis, 5.25% NaOCL, or the control group demonstrated statistically significant differences (p&lt; 0.05), while details reproduction and compatibility with gypsum revealed statistically no significant differences (p &gt; 0.05). Conclusion Within the parameters of this study, the addition silicon can be immersed in 16 mg/ml propolis for 10 min. to disinfect it without compromising its dimensional accuracy, detail reproduction, compatibility with gypsum products, surface roughness, or wettability.

Impact of process parameters on improving the performance of 3D printed recycled polylactic acid (rPLA) components

The main goal of this research was to investigate the influence of additive manufacturing (AM) printing parameters on the mechanical properties and surface roughness of specimens fabricated using recycled polylactic acid (rPLA). In order to achieve this goal, significant printing parameters such as layer thickness, infill density, and nozzle temperature were selected based on prior research. A three-level L9 orthogonal array, based on the Taguchi method, was used in the experimental design. The mechanical properties of virgin PLA and recycled PLA printed specimens were examined and compared. To facilitate the analysis of variance (ANOVA) examination, the response data for mechanical and surface roughness parameters were transformed to signal-to-noise (S/N) ratios. The inspected responses under consideration were the surface roughness, shore D hardness, tensile strength, flexural strength, and impact strength. The main findings suggest that careful consideration of the layer height is crucial for achieving optimum mechanical properties in the recycled PLA specimens. Furthermore, the nozzle temperature also played an important factor that affected the mechanical and surface roughness properties of the 3D printed PLA specimens. Microscopic investigation demonstrated that the number and size of voids increased significantly when the layer thickness and temperature were low, namely, 0.1 mm and 195 ℃, respectively. Finally, the optimal combination of printing parameters for each performance characteristic was determined. Following this, a confirmation test was performed using the preferred combination of parameters, which indicated a strong correlation with the outcomes predicted statistically. The results obtained from this study revealed that recycled PLA exhibited mechanical properties comparable to that of virgin PLA under certain conditions. In summary, the results of this study will serve as a valuable dataset in the field of additive manufacturing, providing valuable insights for other researchers working with recycled PLA material.

Investigation on surface characteristics of wall structures out of stainless steel 316L manufactured by laser powder bed fusion

Pressure equipment poses a high risk of harming people and the environment in case of failure. They are, therefore, highly regulated by the Pressure Equipment Directive. To enable laser powder bed fusion of metals (PBF-LB/M) for the manufacturing of such components, component appearance and quality need to be characterized and qualified for each specific system. In this study, the surface roughness of wall structures out of austenitic stainless steel (316L) is investigated. Wall structure specimens were produced by four manufacturing systems on different PBF-LB/M machines and with different powder materials. Surface roughness of specimens are compared in the upskin and downskin areas in relation to different slope angles and wall thicknesses. Although different process setups, parameters and powder feedstocks have been used, similarities in the dependency of the surface roughness related to the slope angle and wall thickness can be observed. This work furthermore presents a mechanism-based analytical approach to predict system-specific surface roughness. Particularly, the analytical approach on the influence of slope angle on the surface roughness of the downskin areas has not been covered in publications about PBF-LB/M before. The results of this work enable the prediction of system-specific surface roughness, which is especially important for parts with downskin areas and hidden surfaces without the possibility of additional surface treatment.

Effect of polishing versus glazing of CAD-CAM ceramics on wear and surface roughness of opposing composite resin

Background: This study aimed to assess the effect of polishing versus glazing of computer-aided design-computer-aided manufacturing (CAD-CAM) ceramics on depth of wear and surface roughness of opposing composite resin. Materials and Methods: This in vitro study was conducted on 40 Z250 composite and 40 CAD-CAM ceramic specimens including Celtra Duo, Vita Mark II, e.max CAD, and Vita Suprinity ceramics. All ceramic specimens were roughened by a fine-grit bur after primary glazing to simulate an adjusted surface in the clinical setting. They were then randomly assigned to two subgroups and underwent reglazing or polishing. All composite and ceramic specimens underwent profilometry after surface treatment and prior to the wear test, and the results were recorded quantitatively. Composite specimens were then subjected to 120,000 wear cycles against ceramic specimens in a chewing simulator, and the depth of wear was measured by a scanner. Data were statistically analyzed by repeated measures two-way analysis of variance (ANOVA) and one-way ANOVA (α = 0.05). Results: Comparison of the surface roughness of composite specimens before and after the wear test revealed significant differences in both glazed Suprinity (P = 0.048) and Vita Mark II (P = 0.026) ceramics groups. The change in surface roughness after the wear test (compared with baseline) was significant in glazed (P = 0.000) and polished (P = 0.013) Vita Mark II and polished Suprinity (P = 0.037) ceramics, but this change was not significant in other ceramics (P &gt; 0.05). The depth of wear after the wear test was not significantly different among the ceramic and composite subgroups (P &gt; 0.05). Conclusion: Assessment of depth of wear and surface roughness of composite specimens showed that the polishing kits of CAD-CAM ceramics can serve as a suitable alternative to reglazing.

Effect of Heat Treatment Duration and Cooling Conditions on Flexural Strength and Surface Roughness of Cobalt-Chromium Alloys produced by Selective-Laser-Melting

Post-heat treatment may enhance mechanical properties of selective laser melting (SLM) Cobalt chromium (Co-Cr) alloys, however it is unknown what duration the heat treatment needs to last and how the rate of cooling impacts the alloy's flexural strength and surface roughness. In this study, SLM Co-Cr alloy specimens were heated at 1150 C for 1 or 6 hours and subsequently cooled by air cooling (AC), furnace cooling (FC), or water quenching (WC). Flexural strength and surface roughness were then tested. Aim of this study: Investigate the effect of heat treatment and different cooling conditions on the flexural strength and surface roughness of SLM Co-Cr alloy specimens. The heat treatment will be conducted at 1150 C for two different durations (1-hour and 6-hours) and under three cooling conditions (AC, FC, and WC). Materials and methods: A total of forty-two rectangular specimens, measuring (34×13×1.5 mm) were manufactured through SLM and divided into seven groups, six specimens for each group as follows: The first group denoted as control with no heat treatment and no cooling applied, second and third groups heated for 1 or 6 hours then cooled in the air (AH-1 and AH-6), fourth and fifth groups heated for 1 or 6 hours and left inside the furnace until they cooled (FH-1 and FH-6), sixth and seventh groups heated for 1 or 6 hours and cooled by water quenching (WH-1 and WH-6). Flexural strength and surface roughness tests were performed on the specimens. A flexural strength value of (2147.33 MPa) was indicated that the control group exhibited the highest flexural strength, whereas the FH-6 group exhibited the lowest flexural strength value (1282.66 MPa). The control group showed the worst surface roughness (1.63 μm) while all other groups demonstrated no significant differences in surface roughness ranging from (0.32 to 0.49 μm) with a slight increase in the 6-hours heated groups. Conclusions: Slow cooling rate inside the furnace affects flexural strength negatively. Therefore, a high cooling rate is recommended to get a better flexural strength. On the other hand, surface roughness results suggests that 1-hour is better than 6-hours in terms of heat treatment duration and time saving

The Effect of Se ect of Several Electric Cigar al Electric Cigarette Puffs on Nanohybrid ette Puffs on Nanohybrid Composite Resin Surface Roughness

Nanohybrid composite resin is a dental restorative material comprising micro and nano-sized fillers. When accompanied by smoking habits, it can alter the surface roughness of composite resin. Objective: This study aimed to determine the effect of several electric cigarette (e-cigarette) puffs on the surface roughness of nanohybrid composite resin. Methods: This study was conducted in the experimental laboratory with a pretest-posttest control group design using 48 nanohybrid composite resin specimens divided into six groups. Subsequently, the experimental groups were exposed to 75, 150, 225, 300, and 450 puffs of e-cigarette, and the control group was given artificial saliva immersion without exposure for 21 days. The surface roughness of specimens was measured with a surface roughness tester and evaluated through statistical analysis, including One-Way ANOVA and Post-Hoc LSD. Results: The average pre-test and post-test differences between groups I, II, III, IV, V, and VI were 0.013, 0.022, 0.033, 0.044, 0.065, and 0.005 μm. These results showed a significant difference in the surface roughness of nanohybrid composite resin (p &lt; 0.05), with variations between all groups. Conclusion: This study showed that the number of e-cigarette puffs had a significant effect on the surface roughness of nanohybrid composite resin. Specifically, an increase in the number of e-cigarette puffs led to a rise in the surface roughness value of nanohybrid composite resin.

Experimental investigation of surface roughness of CT3 steel on adhesion strength of ARC spray Al -Mg alloy coating

Thermal spray-applied AlMg alloy coatings are frequently utilized in a variety of technical applications because of great corrosion resistance, and environmental friendliness. In this work, the effect of abrasive spraying parameters on the surface roughness of CT3 steel specimens as well as the effect of the surface roughness on the adhesion strength of Al-Mg alloy spray coating were experimentally investigated. The surface roughness was assessed using a portable roughness gauge. The adhesion strength of the coating was evaluated by the pull-off test, according to the JIS H8664-1977 standard. The experimental findings indicate that air pressure and spraying distance have great impacts on the surface roughness of CT3 steel. The adhesion strength of the Al-Mg coating applied on CT3 steel is found to be almost linearly proportional to the surface roughness. The maximum adhesion strength of 14 MPa was achieved at the highest Rz of about 61 µm.