Surface Roughness Of Composites Research Articles

Experimental study on the coefficient of restitution of grain against block interfaces for natural and engineered materials

The coefficient of restitution (COR) is an important input parameter in the numerical simulation of granular flows, as it governs the travel distance, the lateral spreading, and the design of barriers. In this study, a new custom-built micromechanical impact loading apparatus is presented along with impact experiments on engineered and natural materials. The COR and energy loss of various grains and base block combinations are studied, including fairly regular-shaped Leighton Buzzard sand (LBS) grains as a natural soil and granite or rubber as base blocks, apart from the use of engineered materials for the grains (chrome steel balls, glass balls) and blocks (stainless steel, brass). The repeatability of the new micromechanical impact loading apparatus was checked by impacting chrome steel balls on stainless steel block. In all the test combinations, the higher and lower values of the COR are found for granite block (ranging between 0.75 and 0.95) and rubber block (ranging between 0.37 and 0.44) combinations, respectively. For the tested grain–block combinations, lower values of COR were observed for impacts between materials of low values of composite Young’s modulus. However, within the narrow range of composite surface roughness of the tested grain–block interfaces no particular trend was observed in the COR values. Compared to glass balls and chrome steel balls, greater scatter in the COR values is observed for natural sand grains. This is due to the variation of the elastic and morphological characteristics among individual LBS grains.

Color Shift, Color Stability, and Post-Polishing Surface Roughness of Esthetic Resin Composites.

The aim of this study was to compare color shift, color stability, and post-polishing surface roughness of esthetic restorative materials. Twenty-five disc-shaped specimens (10 mm in diameter and 2 mm in thickness) from five esthetic resin materials (Z250XT, IPS Empress-Direct, G-ænial, Vit-l-escence, and Ceram.X) were fabricated. Color shift before and immediately after light-curing (∆E0) then color stability after immersion in tea, coffee, berry juice, and distilled water were measured using a spectrophotometer. Color changes were measured after 2 (ΔE2), 4 (ΔE4), 6 (ΔE6), and 8 weeks (ΔE8). Surface roughness values (Rq) were determined using an optical profilometer after polishing using a rotary polishing system. Data were analyzed using ANOVA and multiple comparison methods at 0.05 significance level. There were no significant differences between the tested materials regarding color shift except between Vit-l-escence and Ceram.X (p = 0.033). There was no significant difference between coffee and tea solutions (p = 1.0) and between berry juice and distilled water (p = 0.15). There was no difference between the tested materials regarding Rq (p = 0.057). Ceram.X was associated with the lowest ΔE8 values overall. Tested materials were comparable regarding color shift and post-polishing surface roughness. Susceptibility to staining was dependent on the material.

Surface properties and bacterial adhesion of bulk-fill composite resins

ObjectivesThe aim of the present study was to evaluate the Streptococcus mutans and Streptococcus mitis adhesion and related surface properties of bulk-fill resin composite. MethodsFour novel bulk-fill composite with different composition were used; Sonic Fill-2 (KSF), Filtek BulkFill (FBF), Admira Fusion X-tra (AFX), Beautifil Bulk Restorative (SBB) and a control group (glass) were included in the study. After standardized surface polishing procedure, surface properties of composite specimens were evaluated using surface roughness (SR) measurements by a profilometer, hydrophobicity and surface free energy (SFE) analyses, elemental and topographic analyses by SEM-EDS. To evaluate the bacterial adhesion, composite specimens were immersed in artificial saliva and mucin for pellicle development. After 1-h immersion, bacterial suspension was added to the pellicle-coated specimens, which were incubated at 37 °C in 5% CO2 atmosphere for 24 h. Adhered bacteria counts were determined as x108 Cfu/ml. Bacterial adhesion was also investigated using confocal laser scanning microscopy. ResultsNo statistically significant differences were found among bulk fill composites in terms of surface roughness while glass showed the lowest Ra values. The lowest contact angle values were found in the control group and Sonic Fill-2 while the highest SFE values were observed in these materials. No statistically significant differences were found between the S. mutans counts. For S. Mitis adhesion, the highest value was found in Sonic Fill-2 and no significant differences were observed between the other groups. ConclusionsSR of bulk-fill composite resins had no effect on bacterial adhesion. However, bacterial adhesion increased with higher SFE values. Clinical significanceAlthough the surface roughness of composites used in the study is similar, in clinically, S. mitis adhesion may be more in the KSF group because of high surface free energy.

Surface Roughness of Nanohybrid Composites with Different Monomers after Finishing and Polishing with Different Polishing Systems

Background: The most frequently used monomer in commercial composite resins is bisphenol A glycidyl dimethacrylate. Bisphenol A glycidyl dimethacrylate free monomer and the long chain dimer acid based monomer were considered as an alternative method to improve mechanical and physical properties of composite resins. Objective: To study the surface roughness of different nanohybrid composites with different monomer compositions after finishing and polishing with different polishing systems. Materials and Methods: 72 composite disk specimens were prepared and divided into 3 groups (n=24) according to the resin composite that were used (harmonizekerr,venusdiamondheraeuskulzerandn'duranceseptodont). Each group was subdivided into 4 subgroups (n=6) according to the polishing technique that was used (Jiffy natural universalwheelsultradent,sof-lexspiral wheels 3mespe,hilusterkerrorenhance systemdentsply). Atomic force microscope was used to measure surface roughness. Results: There was statistical significant difference in surface roughness measuring among differentn'durance,venusdiamondandharmonizegroups (Kruskal Wallis Test p<0.05). Post hock pairwise comparison revealed thatvenusdiamondshowed statistically significant higher surface roughness when compared with eithern'duranceandharmonize. Among the polishing systems,jiffynaturaluniversalwheelsproduce the least surface roughness. Conclusion: Different monomer compositions may have direct effect on the final surface polish of the restorative materials. Clinical significance: The use ofjiffy natural universalwheelsmay be found to result in the smoothest surface finish with the least clinical steps.

Evaluation of Surface Roughness, Hardness, and Gloss of Composites After Three Different Finishing and Polishing Techniques: An In Vitro Study.

IntroductionThe purpose of this in vitro study was to evaluate the effect of three different polishing systems on the microhardness, surface roughness, and gloss of resin composites.Materials and MethodsThe materials evaluated were 3M™ ESPE™ Filtek™ Z-350 XT (3M™, St. Paul, MN, USA), Grandio (Voco, Cuxhaven, Germany), 3M™ ESPE™ Filtek™ Z250 (3M™, St. Paul, MN, USA), Shofu-Beautifil Flow (Shofu, Kyoto, Japan), and RestoFill HV N-FLO (Anabond Stedman, Chennai, India). A total of 450 samples were fabricated. Three finishing and polishing systems: PoGo® (Dentsply Caulk, Milford, DE, USA), Sof-Lex Spiral, and Sof-Lex Pop-On (3M™, St Paul, MN, USA) were evaluated. Hardness, roughness, and gloss were evaluated after finishing and polishing. The surface roughness was measured with a surface profilometer, microhardness was measured with the Struers Duramin-5 microhardness tester (Struers A/S, Ballerup, Denmark) and gloss was measured using a gloss meter. The measurement values were analysed by Kolmogorov-Smirnov, Shapiro-Wilks test, and two-way ANOVA.ResultsThe Sof-Lex Spiral group exhibited higher mean microhardness (p < 0.001), less surface roughness (p < 0.001), and higher gloss (p < 0.001). Filtek Z-250 exhibited higher mean microhardness (p < 0.001) than Grandio (p < 0.001) and Shofu Beautifil Flow (p < 0.001), and Filtek Z-350 XT exhibited more microhardness than Shofu Beautifil Flow (p < 0.001). Filtek Z-350 XT exhibited lower mean surface roughness than Filtek Z-250 (p < 0.05). Filtek Z-250 polished with Sof-Lex Spiral proved to have higher gloss (34.89 gloss units (GU)) than Grandio and RestoFill HV N-FLO (p < 0.05).ConclusionsHardest, smoothest, and glossiest surfaces were obtained with the Sof-Lex Spiral finishing/polishing system. The mean microhardness of Filtek Z-250 and Filtek Z-350 XT was found to be higher than other composites used in this study. Filtek Z-350 showed a lower mean surface roughness and Filtek Z-250 exhibited a higher mean gloss.

Investigation of hole quality in drilled Ti/CFRP/Ti laminates using CO2 laser

The machinability of titanium (Ti) and carbon fiber reinforced plastic (CFRP) (Ti/CFRP/Ti) laminates using CO2 laser is presented in this work. The effect of line energy and laser frequency on output responses such as heat affected zone (HAZ), taper angle (TA), metal composite interface (MCI) damage, surface roughness, dross height, and circularity were investigated. Line energy - the most influential parameter - demonstrated a threshold behavior; no drilling was observed below a certain line energy. Scanning acoustic microscopy (SAM), scanning electron microscopy (SEM), micro-computed tomography (μ-CT), and other imaging techniques were used to establish a correlation between laser parameters and CO2 laser machined damage in Ti/CFRP/Ti laminates. The results show that using a higher frequency and lower line energy can significantly improve the hole quality. However, dross free holes with minimum taper can be obtained using higher line energy.

An Investigation on Anti-Corrosion Properties of Electroplated Copper-Graphene Nano-Composite Films

In this report, graphene sheets used as reinforcements for improvement of anti-corrosion properties have been synthesized by electrochemical intercalation and exfoliation process. The (001) and (002) plane of graphene sheets at a 2θ angle of 13.2 and 26.13 confirmed by X-ray diffraction pattern. High-resolution TEM confirms 8-12 layers of graphene present in the final products. The as-received graphene sheets have been used as reinforcement with copper matrix to synthesize Cu-Gr nanocomposite by electrodeposition method. The results and investigations of Cu-Gr composite thin films deposited from the bath containing 0.1g/L and 0.5g/L graphene concentrations with acidic copper sulfate solution have been compared. The surface morphology and roughness of composites were studied by SEM, AFM and surface profiler. The presence of graphene in Cu-Gr nanocomposite confirmed by EDS analysis. It was observed that the reinforcement particle has increased the mechanical properties of Cu-Gr composite (by 30%) with the addition to the copper matrix. The corrosion resistance of sample was studied by Tafel extrapolation method in standard borate buffer solution. For nanocomposites of 0.5g/L graphene, the values of Tafel constants are, βa=177.37 mv, βc=138.51 mv, Icorr = 9.3165×10-7Amp/cm2, Ecorr = -0.051 volts and corrosion rate 0.01028 mm/a as comparison to the corrosion rate of pure electroplated copper of a value of 0.029 mm/a. The corrosion rate of 0.5g/L Cu-Gr composite was found to be decreased by 2.7 times as compared to pure copper thin films. The structure of the films before and after corrosion was also analyzed to co-relate the electrochemical and structural relationship.

Comparative evaluation of the depth of cure and surface roughness of bulk-fill composites: An in vitro study.

Composites are in great demand due to the esthetic needs of the patients, which explains a wide variation in the types of available composites. However, the mechanical strength of the materials is questionable. Therefore, the mechanical properties of the newly available bulk-fill composites have been tested. The main objective of the study was to compare the depth of cure (DOC) and surface roughness of 3 different bulk-fill composites: X-tra fil® (XTF), Tetric EvoCeram® Bulk Fill (TEC) and Beautifil® Bulk Restorative (BBR). Fifty-seven (n = 19 in each group) samples were made using brass molds. All samples were subjected to Vickers hardness testing and profilometry. The one-way analysis of variance (ANOVA) test was used for the data analysis, followed by Tukey's post hoc test. The differences in the mean surface microhardness values of the materials were statistically significant (p < 0.001), with XTF showing the highest value. The TEC composite showed a higher surface roughness as compared to BBR and XTF. The results of the present study indicate that variations in the filler size and amount significantly influence the DOC and surface roughness of dental composites. Among the tested composites, the multi-hybrid composite exhibited superior DOC (XTF), whereas the nanohybrid composite exhibited superior surface finish (TEC).

Screw withdrawal resistance and surface roughness of woven carbon and glass fiber-reinforced wood-plastic composites

Wood-plastic composites (WPCs) have become one of the most remarkable materials for construction in recent years. Along with high resistance against biological threats, the high mechanical properties are also desired from WPCs as well. In this study, polypropylene (PP) and polyethylene (HDPE) based flat-pressed WPC specimens were reinforced with woven fiber fabric to gain higher mechanical properties. Woven fabrics were located 20% (w/w) below for both surfaces. Carbon fiber and glass fiber woven fabrics, known to have high mechanical properties, were preferred to improve screw withdrawal resistance (SWR) of WPC. Specimens were produced with different wood flour contents (40, 50, and 60%). Results indicated that the increase of SWR reached up to 83%. The highest increase was obtained from carbon fiber for PP, while it was glass fiber for HDPE fabric. The coupling agents had a positive effect on SWR. This study also showed that PE based WPCs had higher SWR compared to PP based ones. Moreover, as wood flour content increased, SWR decreased. The surface roughness of WPCs was also investigated. Contrary to SWR, the wood flour content positively affected the surface roughness; i.e., as wood content increased, surface roughness of WPCs increased. The structure of specimens were also examined using SEM.

Characterization of Lubricated Friction Behavior of Thermal Spray Steel Coatings in Comparison with Grey Cast Iron

This work examines friction properties of smooth-honed thermal spray (TS) low carbon steel coatings produced on an Al-9.0% Si alloy using a plasma transferred wire arc (PTWA) method and an AISI 1010 wire used as feedstock in comparison with the ASM type D grey cast iron (CI) samples subjected to the same (smooth) honing process. CI samples prepared using a standard honing process were also tested for comparison. Reciprocating sliding tests were performed using a Cameron–Plint tribometer against CrN-coated counterfaces within a speed range of 0.06–1.20 m/s covering the boundary and mixed lubrication conditions. Stribeck curves were constructed to show the coefficient of friction (COF) variations with the ratio (λ) of lubricant film thickness to composite surface roughness of TS and CI samples at the mid-stroke position where sliding speeds and surface roughnesses were measured. Examination of the Stribeck curves showed that the TS coated surfaces provided lower COF values compared to CI surfaces given the same smooth honing treatment, e.g., for λ = 2.7 a COF of 0.029 was observed for TS and 0.035 for CI, whereas conventional honing of CI provided a COF of 0.047 under the same condition. Metallographic evidence was given for the surface features and formation of tribolayers on the contact surfaces. The arithmetic mean heights of the surfaces, Sa measured after the tests remained similar for the smooth-honed TS and CI samples. The low COF values of the TS samples were discussed in terms of the surface pores generated during their manufacturing process, and the high oil retention depth ratio (Svk/Sk) of the TS coated surfaces due to the presence of these pores.

Is Deterioration of Surface Properties of Resin Composites Affected by Filler Size?

Purpose To investigate the effect of filler size on surface gloss and roughness of resin composites using a glossmeter and 3D noncontact surface topography, respectively, before and after tooth-brushing abrasion. Materials and Methods Seven model resin composites and one commercial were tested in the study. All materials were first polished, and then the surface gloss and 2D and 3D roughness parameters were recorded. Materials are then subjected to abrasion in a tooth-brushing simulator. Roughness parameters were recorded after 10,000 cycles, and after 20,000 cycles, both roughness and gloss were recorded. One-way ANOVA and Bonferroni post hoc test (p < 0.05) were used to analyze data. Conclusion Filler size is strongly correlated to gloss and surface roughness retention.

Effect of shot peening on surface properties of Al7075 hybrid aluminum metal matrix composites

Various fields of engineering such as automobile, aerospace and construction industries are employs Aluminum alloys and its composites due to its high strength to weight ratio. But they possess poor wear resistance due to low hardness. In this research, shot peening treatment is used to enhance the wear resistance ability of the composites. Micro hardness and surface roughness of AL7075 Hybrid metal matrix composites are examined after shot peening treatment. For this, the aluminum alloy specimens are subjected to shot peening for 30, 60, 90, 120 and 150 s time. The results reveal that the shot peening treatment increases micro -hardness and surface roughness up to 90 s. The specimen after 120 s peening demonstrates the marginal improvement in micro hardness and slight reduction in surface roughness.

Effect of water-jet flossing on surface roughness and color stability of dental resin-based composites

BackgroundThe purpose of this in vitro study was to investigate the effects of water-jet flossing on the color stability and surface roughness of five resin-based composites. Material and MethodsFive commercially available composite resins were studied. Nine disc-shaped specimens (6x2mm) were fabricated from each composite. The specimens were randomly allocated into three groups and three different treatments were performed on each group: storage in water (control group), water-jet flossing using 50 Psi water pressure, and water-jet flossing using 100 Psi water pressure. The water-jet flossing was performed in a standardized manner using a Waterpik® Aquarius® water flosser. Color and roughness were measured at baseline and at the end of 30 minutes of treatment, which is approximately equivalent to 5 years of simulated water-jet flossing for 1 minute once a day. The data were statistically analyzed using two-way analysis of variance (ANOVA) with Bonferroni and Tukey’s post-hoc tests. ResultsNo significant color change was found after 5 simulated years of water-jet flossing, irrespective of composite type and water-flossing pressure setting (p > 0.05). Furthermore, none of composite specimens showed any significant surface roughness changes except for the two composites with spherical filler specimens in the 100 Psi treatment group. These composites exhibited a significant increase in surface roughness compared with the nano-filled composite (p = 0.001 and p = 0.006). However, the differences were clinically acceptable (≈0.2 µm). Conclusions In terms of surface roughness and color, water-jet flossing is safe to be used on composite restorations within the settings of this study. Key words:Color difference (∆E), resin composites, surface roughness, water flosser.

Surface quality and color stability of posterior composites in acidic beverages.

Context:Consumption of acidic beverages has been reported to alter the physical and esthetic properties of resin composites, which in turn can affect clinical success.Aims:This study aimed to evaluate the effect of acidic beverages on surface roughness and color stability of Filtek™ Bulk-Fill posterior restorative composite in comparison with Filtek P60 posterior restorative composite.Settings and Design:Ninety composite discs were used for surface change analysis and another ninety were used for color change analysis.Materials and Methods:Ninety Filtek P60 and Filtek Bulk-Fill composite discs were fabricated and divided into three subgroups according to the solutions – artificial saliva (control group), orange juice, and Coca-Cola® (test groups). The samples were immersed in each beverage for 10 min each day for 56 days. To measure the surface roughness, a profilometer was used, and the surface was qualitatively analyzed using a scanning electron microscope. A reflectance spectrophotometer was used for assessing the color change.Statistical Analysis Used:Two-way analysis of variance was used to compare the surface alteration and color change values between the two composite groups and their respective three subgroups. Tukey's multiple post hoc test was performed for pair-wise comparison.Results:Filtek P60 had exhibited higher color change than Filtek Bulk-Fill in all immersion solutions. Coca-Cola resulted in highest staining in both the composites.Conclusions:The surface roughness and color change of both composites increased significantly in acidic beverages and more in Coca-Cola. Bulk-fill exhibited better surface quality and color stability than P60.

Analysis of Characteristics of Surface Roughness of Machined CFRP Composites

Measuring and characterizing of surface roughness of machined surfaces of carbon fiber reinforced polymer (CFRP) composites are difficult due to the occurrence of special surface damages (delamination, uncut fibers, fiber pull-outs or micro-cracks, etc.). The main objective of the present study is to analyze the characteristics of surface roughness of machined unidirectional CFRP in detail. Numerous conventional drilling, helical milling, and edge trimming experiments were carried out with different cutting tools in order to analyze the influence of them on the average surface roughness (Ra), on the roughness depth (Rz) and on the Rz /Ra parameter. The surface roughness was measured by a Mitutoyo SJ-400 contact profilometer and an Alicona Infinite Focus confocal microscope. The usability of the contact profilometer was experimentally tested and compared its results with the results of the confocal microscope. Experimental results show that the contact profilometer is suitable for measuring surface roughness of CFRP, furthermore, values of Rz /Ra of drilled and edge trimmed surfaces of unidirectional CFRP are changing in a wide interval: from 5 to 14 μm/μm due to the special surface damages. Based on this research, the machinability analysis of CFRP is suggested to be extended to the analysis of the Rz /Ra parameter.

The effect of glycerin on the surface hardness and roughness of nanofill composite

Background: Present research studied the surface hardness and roughness dependence on polymerization. Polymerization of composites occurs through chain reaction that is induced by free radicals. Oxygen in the air decreases the excitability of the photo initiator, causing polymerization interference. Oxygen inhibition layer (OIL) is formed on the surface. OIL can be reduced by curing the composite through by application of glycerin to the surface. Purpose: To determine the effect of glycerin on the surface hardness and roughness of nanofill composite. Material and Methods: 64 specimens of composite (Z350 XT, 3M) were prepared using a disc-shaped acrylic. The groups were divided into group A surface hardness (N=32) and group B surface roughness (N=32). Group A1, the specimen was coated with glycerin and light cured for 20 s and group A2, the specimen was exposed to air and light cured for 20 s. Group B1 was coated with glycerin and light cured for 20 s and Group B2 was exposed to air and light cured for 20 s. The specimens were stored in distilled water for 24 h at 370. Measuring with Vickers and surface roughness tester and. Data were statistically analyzed using Mean-whitney U Test. Results: There were statiscally significant difference between the surface hardness and roughness of nanofill composite coated with glycerin and without glycerin (p&lt;0,05) Conclusion: The surface hardness of nanofill composite resin coated with glycerin is higher than composite without glycerin and the surface roughness of nanofill composite resin coated with glycerin is lower than composite without glycerin

A COMPARATIVE STUDY ON SURFACE CHANGES BETWEEN COMPOSITE VENEER AND ACRYLIC RESIN USING BATTERY- OPERATED TOOTHBRUSH AND MANUAL TOOTHBRUSH

Early forms of toothbrush have been in existence since 3000 BC. Several changes have happened since then, it has evolved from a‘chew stick’, into a bristle toothbrush, then a battery-operated toothbrush. Tooth brushing has been our primary way of cleaning theoral cavity and its structures to maintain good oral hygiene. However, prolonged brushing can be abrasive to one’s existing restorationand prosthesis increasing the surface roughness, leaving the resins vulnerable to damage and plaque accumulation. This study aims toevaluate the effect of tooth brushing using a manual toothbrush and a battery-operated toothbrush to the surface roughness ofcomposite resin restorations and denture base acrylic resin. Composite specimens and denture base acrylic specimens showed varyingwear and surface roughness with several variables taken into consideration such as brushing force, brushing stroke, dentifrice, type ofbristle, and type of toothbrush used. The expected result is that the specimens brushed using the battery-operated toothbrush withapplied toothpaste will have greater wear and surface roughness.

Direct injection molding of hybrid polypropylene/wood-fiber composites reinforced with glass fiber and carbon fiber

Wood-plastic composites (WPC), made of wood fiber (WF) and thermoplastics, have been well developed and commercialized in construction, packaging, automotive, and furniture industry over the past three decades, as they are environmentally friendly and require less maintenance compared with natural wood. Polypropylene (PP) is one of major thermoplastics used in WPC. However, the relatively poor mechanical properties of WPC prevent them from penetrating into other structural applications where strong mechanical properties are required. To enhance the mechanical properties of PP/WF composites, this paper applies one-step direct injection molding to produce the hybrid WPC with glass fiber (GF) and carbon fiber (CF). Compared with those of PP/WF composites, the tensile strength and tensile modulus of PP/WF/GF hybrid composites increased 30% and 26%, respectively, and the tensile strength and tensile modulus of PP/WF/CF hybrid composites increased 38% and 78%, respectively. Apart from the significant increase of mechanical properties, the additional benefit of hybrid WPC was that their flame-retarding property was improved. Particularly, the dripping behavior (or fire spreading) during burning associated with WPC was significantly reduced or eliminated for the hybrid composites. In addition, the water absorption and the surface roughness of hybrid composites were also studied. This study demonstrates that it is feasible to make hybrid WPC with one-step injection molding, and hybrid WPC open the door to their potential structural applications.

Effects of Finishing and Polishing Methods on the Surface Roughness and Surface Free Energy of Bulk-fill Resin Composites.

The purpose of this study was to determine the influence of finishing and polishing methods on surface properties of bulk-fill resin composites through surface roughness (Ra) and surface free energy (SFE) measurements, and scanning electron microscopy (SEM) observations. Three bulk-fill resin composites, Tetric EvoCeram Bulk Fill (TB), Filtek Bulk Fill (FB), and Filtek Bulk Fill Flowable Restorative (FF), and two conventional resin composites, Clearfil AP-X (AP) and Estelite ∑ Quick (EQ) were used. Seventy cured specimens of each resin composite were prepared and divided into seven groups of 10 specimens. Ra, SFE measurements, and SEM observations were conducted after finishing and polishing procedures. Three groups of specimens were finished with a fine grit diamond bur (FDB), and three with a tungsten carbide bur (CBB). After finishing, one group from each type of finishing was polished with aluminum oxide flexible disks (SSD) and one group from each type of finishing was polished with diamond particles embedded in a silicone point (CMP). A baseline group of samples that were neither finished nor polished after removing the translucent strips from the surface was examined. Although the baseline group showed significantly lower Ra values than the other groups, most resin composites showed lower Ra values with CBB+SSD than with the other finishing and polishing groups. Among the tested resin composites, EQ showed significantly lower Ra values than the other resin composites, regardless of the finishing and polishing methods. On the other hand, AP showed significantly higher Ra values than the other resin composites in all finishing and polishing groups, apart from FB with FDB. For the finished specimens, most resin composites showed higher SFE values with CBB than with FDB. For the polished specimens, all the tested resin composites with CMP showed lower γS values than those with SSD, regardless of the finishing method. The baseline groups of TB and FB showed significantly lower SFE values than the other finished and polished groups. In the SEM observations, all the examined resin composites showed rougher surfaces after finishing with FDB than with CBB. However, when comparing the different polishing methods (CMP and SSD), surface smoothness appeared to be material dependent.

Abrasive waterjet machining of Ti/CFRP/Ti laminate and multi-objective optimization of the process parameters using response surface methodology

In present work, abrasive waterjet machining has been used to machine adhesively bonded titanium-carbon fiber-reinforced plastics-titanium hybrid laminate with varying traverse speed, jet pressure, and stand-off distance. The effect of varying abrasive waterjet machining parameters on cut quality has been quantified by material removal rate, metal composite interface damage factor, taper ratio ( T r), and surface roughness (Ra). Response surface methodology along with central composite design has been used to analyze the influence of process parameters on output responses. Additionally, analysis of variance was performed to identify the significant parameters on the output responses. For better abrasive waterjet cut quality, the optimal values of process parameters obtained were 200 MPa jet pressure, 237.693 mm/min traverse speed, and 1 mm stand-off distance. The corresponding material removal rate, metal composite interface damage factor, taper ratio, and surface roughness are 5.388 mm3/s, 1.41, 1.16, and 3.827 µm, respectively. Furthermore, validation tests have been performed with obtained optimal parameters that deliver satisfactory outcomes with an error of 5.35%, 3.07%, 2.29%, and 0.39% for material removal rate, metal composite interface damage factor, taper ratio, and surface roughness, respectively.