Finishing Techniques Research Articles

Improving the performance of silver coating deposited on copper through corrosion inhibitors

Immersion silver plating is an important surface finishing technique in the integrate circuit industry. However, it often results in silver coatings with poor compactness and adhesion due to the significant difference in potentials between silver and copper. The corrosion inhibitors of copper, rather than complexing agents of silver ions, were used to improve the immersion plated silver coating performance on copper. It was found the combined use of benzotriazole and imidazole could regulate the erosion rate of the copper substrate and improve the quality of the silver coating. The effects of different inhibitors concentrations on surface morphology, elemental composition, corrosion resistance, hardness, and conductivity of the silver coating were studied. The results indicated the optimal concentration of the combined inhibitors was 0.058 mol∙L-1, which enhanced the compactness, crystallinity, and overall performance of the silver coating by passivating the copper surface and regulating the silver deposition process.

Surface finishing of 3D-printed Ti–6Al–4 V alloy by electrolyte plasma polishing: Process optimization and microstructure

The electrolyte plasma polishing (EPP) technology is proposed to remove the unmelted powder particles and oxide film for high-quality surface finishing of 3D-printed Ti–6Al–4 V alloy. An orthogonal experiment is conducted to investigate multiple factors that contribute to the surface quality of the alloy during the polishing process. The optimal parameters determined for the EPP process are a voltage of 300 V, a polishing time of 12 min, a polishing depth of 12 cm, and a temperature of 75 °C. Based on the extent of the effect, the factors influencing surface roughness were ranked: voltage > time > depth > temperature. The surface crest and trough area of the alloy is substantially reduced after polishing, while the average roughness experienced a reduction of 76 %. The improvement in surface quality is attributed to the corrosion of the oxide layer by F ions in the electrolytic solution, and the melting of surface protrusions due to the impact of high-energy electrons under high-temperature and high-pressure conditions during plasma discharge. Additionally, the surface hardness of the material decreases slightly, but its corrosion resistance and hydrophobicity are enhanced, and the calibration rate of the EBSD sample can reach 92.51 %, demonstrating that it is an excellent surface finishing technique. Hence, EPP is a promising approach for smoothening 3D-printed metals, especially for alloy parts with complex geometry and porous structure.

Regulating mechanisms of external axial magnetic field on flow and heat transfer behavior for process optimization in plasma beam polishing

Plasma beam polishing has emerged as an innovative alternative to conventional metal finishing techniques. However, the precision machining ability of plasma arc encounters challenges due to the formation of surface undulations, while previous research has predominantly focused on parameter adjustments. In this paper, the feasibility of optimizing the plasma beam polishing process was validated through magnetic field regulation, as the surface topography and subsurface structure were obviously flattened. Given this, a micro plasma arc model under inhomogeneous axial magnetic field was established to explore the regulating mechanisms of the external axial magnetic field on the flow and heat transfer behavior of the plasma arc. Through this model, the plasma characteristics (magnetic induction intensity, electric potential, arc current, Lorentz force, plasma velocity and electron temperature) were comprehensively discussed. The results indicate that the external shape of the plasma arc is determined by the self-induced magnetic field, while the externally applied axial magnetic field significantly influences the internal flow of the plasma arc. The axial and radial magnetic fields generated by the excitation coil can induce circumferential rotation by dragging the plasma arc with Lorentz force, creating a more suitable energy beam for the polishing process. To verify the model, the arc temperature was measured using spectroscopic diagnostics, and the arc shape was captured using a high-speed camera, both of which were basically consistent with the simulation results.

Gold and Gold Alloys Electropolishing in Choline Chloride-Glycerol Deep Eutectic Solvents

Electropolishing (EP) is a finishing technique used to reduce the roughness of metallic surfaces while enhancing their brightness. This process enables the treatment of complex shaped parts and reduces processing time compared to conventional mechanical polishing methods. Electropolishing of precious metals typically requires the use of electrolytes containing cyanides and other toxic compounds, which reduces its attractiveness from an industrial perspective. Deep Eutectic Solvents (DES) are emerging as a good alternative for the chemical and electrochemical dissolution of valuable metals, like gold, silver and copper. However, their use in the specific context of electrochemical polishing of precious alloys has not been considered so far. This work aims to evaluate the effectiveness of choline chloride-based DES in electropolishing 18K gold alloys. Their performance will be assessed in terms of roughness reduction, brightness enhancement and color preservation, all characteristics associated with the presence of a uniform dissolution.

MULTIFUNCTIONAL MODIFICATION OF COTTON FABRIC FOR ANTIMICROBIAL, FLAME-RETARDANT AND OLEOPHOBIC PROPERTIES

In recent times, the investigation and development of multifunctional textiles have become a necessity for the textile and apparel industries. Therefore, this paper explores an innovative approach to enhancing the functional properties of cotton (cellulosic) fabric by integrating advanced technologies to impart oleophobic/hydrophobic, flame-retardant, and antibacterial characteristics. The methodology involves systematically applying chemical treatments utilizing a layer-by-layer finishing technique to achieve the desired multifunctionality in cotton fabric. Silver nanoparticles and a phosphorus-nitrogen-based synergistic flame-retarding agent were employed to finish the fabric. Performance testing encompasses evaluating bacterial reduction, contact angle measurements, water absorption properties, flame-retardant capabilities, and Limiting Oxygen Index (LOI). Characterization techniques such as FTIR, SEM, and EDX analysis, were carried out to assess structural and chemical modifications of the material. The results illustrate a notable transformation of the cellulosic fabric, showcasing enhanced resistance to bacterial attack, improved stain resistance, and heightened flame-retardant performance, without compromising its color indices and air permeability. The fabric retains these multifunctional attributes even after 20 cycles of laundering, which confers durability. The implications of this research extend the application of conventional cotton fabric in diverse sectors, including apparel, home furnishings, and industrial textiles.

Effect of finishing and polishing techniques on the fit accuracy and dimensions of conventional and CAD‐CAM removable partial denture frameworks

Effect of finishing and polishing techniques on the fit accuracy and dimensions of conventional and CAD‐CAM removable partial denture frameworks

Evaluating the Effectiveness of the "Double Finish Line Technique" on Full-Crown Retention for Short Abutments: An In Vitro Study.

Achieving clinically adequate retention for cast crowns in prepared short abutments represents a major challenge for practicing dentists. Despite the important developments with adhesive cement, only a few teeth can be treated this way, and conventional preparation techniques are still employed for most crowns. Numerous options for auxiliary features exist; however, there is no consensus about one preferred method. This study aimed to evaluate the effect of a new innovative technique called the "double finish line technique" on full-crown retention for short abutments and to compare it with another modified preparation method. A comparative in vitro experimental study was conducted at the Department of Fixed Prosthodontics, Damascus University. The study sample consisted of 30 chromium-cobalt abutments and 30 metal crowns. The sample was divided into three equal groups. The first group was a control group (CG) with a 20-degree total occlusal convergence, 3 mm height, and a 0.5 mm chamfer finish line. The second group had a reduced total occlusal convergence (TOC) in the cervical 1.5 mm of the axial wall from 20 to 8 degrees. The third group implemented the so-called "double finish line technique," adding another 0.5 mm chamfer finish line 1 mm above the first finish line (DFL group). The metal crowns were cemented to metal dies with zinc-phosphate cement. Pull-off tests were applied until failure. Data were analyzed, and the differences between the three groups were detected using one-way ANOVA followed by Bonferroni's post-hoc tests (p<0.05). The mean tensile strength values for the specimens were 115.36 (SD=14.59), 149.60 (SD=11.10), and 42.46 (SD=11.54) for the TOC, DFL, and CR groups, respectively. The reduced total occlusal convergence and double finish line techniques effectively increased full crown retention and resistance cemented on short abutments.

Optimization of electrolytic plasma polishing process and surface performance analysis for 6061 aluminum alloy

Electrolytic Plasma Polishing (EPP), an innovative technology for polishing, has been utilized to improve the surface performance of 6061 aluminum alloys. An orthogonal experimental approach was carried out to investigate the multiple factors influencing the surface quality of aluminum alloys during the polishing process. The results indicated that peaks and scratches on the surface were successfully removed after polishing, with the average roughness reduced to 0.138 μm, approximately 1/8 of the original roughness. Additionally, the EPP process enhanced the substrate's corrosion resistance and hydrophobicity. Finally, it is proposed that the mechanism of surface smoothing effect of EPP is attributed to the combined action of plasma chemical dissolution and cavitation forces peeling. This research indicates EPP as a promising finishing technique with considerable potential for enhancing the surface performance of aluminum alloys in electronic component applications.

Enhancement of acoustic cavitation streaming: A study on surface finishing of additively manufactured components

Due to the poor surface characteristics of additively manufactured parts, the necessity for post-process surface enhancement is crucial. Among the prevalent post-processing techniques, the acoustic cavitation-based surface finishing technique has recently emerged. Despite a considerable amount of focused research on the material removal mechanisms of this technique, less attention has been devoted to addressing its limitations associated with enhancing the process capability towards achieving a better surface finish. The driving force behind the acoustic cavitation technique is the bubble implosion through cavitation streaming, and the cessation of the acoustic cavitation streaming beyond a certain length is the main limitation. It has restrained the process capability towards finishing both external and internal surfaces. Hence, this research aims to unravel novel ways of employing the acoustic cavitation-generating parameters and achieving better-quality surface finishing of additively manufactured (AM) components. A study has been conducted on different AM materials, including Inconel 625 and aluminum alloy, by introducing various methods associated with acoustic amplitude, working mediums, temperature, and external vibration. The results reveal a significant reduction in average surface roughness for both materials. The topographical and morphological observations confirm the qualitative improvement on the surfaces. In addition, the conical bubble structures that frame the acoustic cavitation streaming are elucidated by implementing high-speed imaging techniques, and their enhancement at different parametric conditions is delineated. Henceforth, the findings suggest a notable insight into the potential of the employed approaches in enhancing the acoustic cavitation streaming for achieving a better surface finish of AM components.

Color stability of precolored and extrinsically colored monolithic multilayered polychromatic zirconia: Effects of surface finishing and aging.

To explore the impact of zirconia types, coloring methods, and surface finishing on the color stability of monolithic multilayered polychromatic zirconia after artificial aging, including thermocycling and simulated toothbrushing. Eighty square-shaped zirconia samples were divided into 2 types (M3Y-TZP and M6Y-PSZ), further categorized based on coloring methods (precolored and extrinsically colored) and surface finishing techniques (mechanical polishing or glazing). The color stability was assessed using the CIEDE2000 formula. Artificial aging was simulated via thermocycling and toothbrushing. All samples were analyzed with a spectrophotometer to determine the post-aging color changes (ΔE00). The ΔE00 were interpreted and classified using the 50:50% perceptibility threshold (PT) and the 50:50% acceptability threshold (AT). Comparisons between groups for ΔE00 differences were performed using three-way ANOVA, with pairwise comparisons facilitated by Fisher's protected least significant difference test, α = 0.05. The study results indicated significant impacts of zirconia type, coloring method, and surface finishing on color stability. The M6Y groups experienced significantly greater color changes (6.61 ± 1.63) compared to the M3Y groups (3.40 ± 2.24), p < 0.0001. For both types of zirconia, extrinsically colored samples exhibited significantly higher ΔE00 when mechanically polished (p = 0.004). However, surface finishing had no significant effect on ΔE00 in precolored samples of either zirconia material (p = 1.000). The evaluation and categorization of ΔE00 variations indicated that nearly all color changes in the M6Y groups, regardless of being precolored, extrinsically colored, polished, or glazed, were deemed extremely unacceptable (Grade 1). In contrast, the M3Y groups showed more acceptable results, with the majority of color changes classified as moderately unacceptable (Grade 3). The color stability of multilayered polychromatic zirconia is influenced by the type of material, extrinsic coloring, and the chosen surface treatment post-artificial aging. The translucent 6Y-PSZ exhibited lower color stability, especially with only mechanical polishing. For the fabrication of M3Y-TZP and 6Y-PSZ monolithic multilayered polychromatic zirconia restorations, extrinsic coloring should be paired with glazing to maintain color stability. Conversely, in the absence of extrinsic coloring, both glazing and mechanical polishing are effective in preserving color stability.

Numerical and experimental investigation into tool-workpiece interaction in flexible abrasive tool finishing

The present work examines the finishing performance of oxygen-free high conductivity (OFHC) copper using a fabricated flexible abrasive tool. It is challenging to finish soft materials like copper and aluminium using traditional finishing techniques due to frequent scratching. Flexible finishing tool can protect the surface integrity of the workpiece samples during finishing action. Flexible abrasive tools are fabricated using solvent casting method. This method fabricates the flexible tools with homogeneous abrasive dispersion and an open-cell porous structure. The developed tool is self-sharpening and self-lubricating and can finish soft materials efficiently. The flexible abrasive tools can be fabricated in different shapes and sizes to finish internal features and complex shapes. The interaction between the tool and workpiece is examined by the forces exerted by the flexible tool on the workpiece. The areal surface roughness of the finished surface is reduced to 33 nm from its initial roughness of 937 nm after 20 min of finishing a pre-defined region. Theoretical analysis is carried out to estimate contact pressure using Hertz contact theory. The results obtained from numerical and theoretical analysis have a close correlation with the experimental results. The maximum deviation of peak contact pressure obtained in theoretical estimation and numerical analysis from experimental results is found to be 20.73 % and 12.83 %, respectively. As the model includes the basic physics of the tool-workpiece interaction, the results can be improved with the inclusion of micro-level analysis of fluid-filled flexible abrasive tools with embedded abrasives.

Examining the impact of slide burnishing parameters on the 3D surface features of medium carbon steel

Burnishing is a non-cutting finishing technique in which pressure is applied to plastically deform the irregularly distributed surface materials. In this process, the peaks of the surface are pressed into the valleys with a hard tool, resulting in a smoother surface with improved properties. The influence of brunishing parameters such as brunishing force, feed rate and number of passes on the 3D surface roughness of medium carbon steel was analyzed. An orthogonal L9 array Taguchi design was used to create a robust experiment. A CNC milling machine and a confocal microscope were used to grind and measure the workpiece surface. The topography roughness responses Sq, Sv, Sz and Sa were used to evaluate the roughness changes. The optimal parameters for brunishing were a feed rate of 0.05 m/min, 2 passes and a force of 80N for Sq and Sa and a force of 100N for Sv and Sz. This research is expected to provide insights into optimizing mass finishing processes to improve surface integrity, contributing to advances in manufacturing and materials science.

Design and development of Rotational Magneto Abrasive Flow Finishing setup powered with machine learning tools for nanofinishing of cylindrical double camshaft followers

Surface finish and morphology play a vital role in the reliability and life of cam-roller or slider mechanisms, with improvement due to lesser contact pressure-based fatigue and failure as surface finish improves. An experimental setup using magnet-based abrasive finishing techniques is designed and developed to conduct studies on a double camshaft follower arrangement that resulted in less than 300 nm finish at an enhanced finishing rate. Finishing rate improves greatly as speed of rotation of the workpiece increases with relatively bigger abrasive particles while the best finish is obtained at lower speeds and particle sizes with progression of the finishing cycles. Subsequently, using the results as the training dataset, a machine learning system is developed to overcome the limitations of surface measurement techniques and human interventions, to predict outcomes like number of cycles, speed of rotation of workpiece, time to reach the desired finish and particle size to be used for the given material of workpiece, initial surface roughness and final desired surface finish. The predictions from the completely trained system are compared with the physics-based model and the real data and the error is found to be within 20 nm which has led to development of a highly reliable system.

Translucency and Color Difference of Monolithic Zirconia Restorations: The Effect of Surface Finishing on Background Color

Aim: This study evaluates the effect of different surface finishing procedures on the color and translucency values of monolithic zirconia materials on three different colored composite backgrounds. Materials and Methods: Sixty monolithic zirconia blocks of three different translucency levels were prepared in vitro using computer-aided design/computer-aided manufacturing (CAD/CAM) systems. The correlation between repeat measurements was 0.5, resulting in a sample size of nine samples per group to detect a medium effect size, f = 0.25. Half of the zirconia blocks in each group were subjected to glazing, while the other half were polished ( n = 10). Composite blocks of three different colors were prepared to simulate dental substrates, and the zirconia specimens were placed on these composite backgrounds. The color parameters of the specimens were measured using a spectrophotometer on gray, black, and white backgrounds. Three-way repeated measure ANOVA was used to assess the interaction between the three independent variables (zirconia brand, surface finishing technique, and background color) and the effects of each tested variable on the changes in color and translucency. Results: The surface finishing techniques had a significant effect on the color and translucency of the monolithic zirconia materials. Glazing resulted in higher color differences and lower translucency values compared to polishing. For backgrounds of the same color, no significant differences were detected between the glazed zirconia groups for the same condition ( p &gt; .016). Conclusion: Overall, the study demonstrated the importance of selecting the appropriate surface finishing technique and translucency property of the monolithic zirconia materials to obtain the optimal esthetic results in dental restorations.

Enhancing the flame retardancy of polylactic acid nonwoven fabric through solvent-free transparent coating

Polylactic acid (PLA) nonwovens, recognized as eco-friendly substitutes for petroleum-based synthetic fibers, face a significant challenge due to their inherent flammability. This work addresses this concern by synthesizing a hyperbranched polyphosphoramide flame retardant (TPDT) through a one-step polycondensation process without using solvent and catalyst. TPDT is subsequently applied to PLA nonwovens using a dip-pad finishing technique. Notably, with a mere 7 wt% weight gain of TPDT, the PLA nonwovens exhibit a substantial increase in the limited oxygen index (LOI) value, reaching 32.3 %. Furthermore, the damaged area in the vertical burning test is reduced by approximately 69.2 %. In the cone calorimeter test, 17 wt% weight gain of TPDT results in a 51.4 % decrease in peak heat release rate and a 56.0 % reduction in total heat release compared to the control PLA. Additionally, char residue increases from 1.5 wt% to 31.1 wt% after combustion. The strong affinity between TPDT and PLA molecules persists even after repeated abrasion, ensuring sustained flame retardancy. Importantly, the introduction of TPDT also imparts increased softness to the PLA nonwovens. This work addresses this concern by synthesizing a hyperbranched polyphosphoramide flame retardant (TPDT) through a solvent-free, catalyst-free, and one-step polycondensation process.

Synthesis and application of silicone-modified polyurethane as a slip-elastic finishing agent for polyamide fabrics

Despite the wide application of polyamide in clothing and home textiles, its inherent stiffness hardly meets consumers' preference for a smooth and elastic hand feel. In this study, a new hydroxyl silane coupling agent (KHS), 1-(4-(4-(4-(trimethoxysilyl)butyl)piperazin-1-yl)-3-(3-(trimethoxysilyl)propoxy) propan-2-ol, was synthesized and used to prepare a series of silicone-modified polyurethane (KHS-PU). KHS-PU then was finished onto the polyamide fabric via a pad-dry-cure procedure. The finishing process was optimized using the Minitab software. The morphology and elemental distribution of KHS-PU finished polyamide fabric were characterized using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), respectively. The hand evaluation tests demonstrated that KHS-PU not only significantly enhanced the fabric's smooth and elastic properties, specifically evidenced by a 23 % reduction in surface friction coefficient, a 13 % decrease in bending average stiffness, a 10 % reduction in compression work, and a 40 % increase in compression recovery rate, but also exhibited good wash durability. In addition, the thermal and mechanical properties of KHS-PU finished fabric were further investigated. This work provides a valuable contribution to the field of surface science and textile engineering, offering insights into advanced fabric finishing techniques.

In‐depth investigation and industry plan for enhancing surface finishing of 3D printed polymer composite components: A critical review

AbstractAdditive manufacturing (AM) is pivotal in modern manufacturing, allowing diverse materials to create functional parts. Polymer composites, with superior properties like enhanced mechanics and conductivity, are highly regarded. Fused deposition modeling (FDM) is a favored, cost‐effective AM technique. Despite popularity, FDM struggles with poor surface quality, impacting final part properties. This challenge affects composite part performance, prompting a need for surface quality enhancements in AM processes, like FDM. The review explores essential post‐treatments required to optimize composite parts for various applications. It examines surface finishing techniques for FDM 3D printed polymeric composites, categorizing them into chemical, thermal, and physical methods. Recent research is extensively analyzed, offering a comprehensive guide for academia and industry. The review covers diverse aspects, including properties, surface morphology, electrical conductivity, and mechanical properties pre‐ and post‐finishing methods. Additionally, it summarizes leading companies worldwide providing surface finishing services for 3D printed polymer parts. Discussions on future trends, challenges, and research gaps in this field are included, emphasizing its significance in refining surface finishing methods for FDM 3D‐printed polymeric composites and encouraging broader industrial adoption of AM. This overview serves as a crucial roadmap for engineers, scientists, customers, and companies interested in surface finishing services.

An Exceptional Late Antique Belt Buckle Plate from Jaffa: From Metalworking Technology to Cultural Biography

Abstract: This paper introduces a technological and cultural biography of an exceptional copper-based belt buckle plate from ancient Jaffa. The exploration of intricate metalworking techniques and the cultural significance of this find provide new insights into late antique material culture in the Levant. Although similar buckles appear in museum collections around the world, few have archaeological provenience and, to date, none have been analyzed and published in terms of their material characteristics. This study establishes a metallurgical database for future comparative analyses, employing X-ray fluorescence spectrometry and scanning electron microscopy with energy-dispersive X-ray spectroscopy to characterize the buckle's composition and manufacture. The results reveal the use of recycled metals, casting, cold fastening, and decorative finishing techniques, including contouring of the openwork shapes. The analysis finds no evidence of enameling, challenging existing theories about these buckles. A comparison of the crafting techniques and design elements of this belt buckle plate with those of similar buckles shows evidence of distinctive artisanal traditions. The socio-cultural inferences of its art and iconography are also explored in light of the geopolitical landscape after the Arab conquests. This study sheds light on the production and distribution of Levantine buckles and enriches understanding of their use in late antique culture and society.

Effect of dry and wet finishing and polishing on color change and opacity of nanofill and nanohybrid composites

BackgroundAs superior esthetic is one of the main reasons for using composite resins, it is very important to be familiar with factors and techniques affecting their optical properties and appearance.AimThe aim of this study was comparing the effect of finishing and polishing with and without water coolant, on the color change and opacity of composite resin materials.MethodsComposites used for preparing samples were Z250 (microhybrid), Z350XT (nanofilled), and Z550 (nanohybrid). Then divided into 4 groups of 5 depending on finishing and polishing technique (dry or wet) and time (immediate and after twenty-four hours). After polishing, samples were assessed using a spectrophotometer. Color change and opacity were determined. Data was analyzed using Kolmogorov-Smirnov, ANOVA and Tukey HSD tests.ResultsType of material at both time had a significant effect on ΔE and opacity. Our results in dry and wet technique immediately(T0) showed that the highest and lowest ΔE and opacity belong to Z350XT (p < 0.001). After Twenty-four hours (T24), opacity of Z250 in wet condition was higher than dry condition (p < 0.001).ConclusionsWet or dry technique was only effective on color in immediate polishing. Regarding opacity, technique was only effective in case of delayed polishing.

Surface quality evaluation through 3D profilometry of dental restoration performed in a clinical simulated environment

This study evaluated the surface quality of Class V composite resin restorations, comparing the surface roughness resulting from applying three techniques for finishing and polishing in a condition of clinical simulated environment by using artificial dental arcade. Beyond the aesthetic aspect, the importance of the surface quality of the restoration is associated with biofilm accumulation that occur on the teeth restored surface depending on the roughness level, leading to carious lesions and gingivitis. The minimum roughness considered ideal to avoid the accumulation of bacterial biofilm, is 0.2 μm, and 0.5 μm for tactile perception. Most of the evaluations of the surface quality of restorative materials are performed in flat specimens, and the results can significantly differ from the clinical scenario. The present work discloses how heterogeneous the surface quality may result when dealing with natural teeth. The finishing and polishing techniques selected in this work comprised diamond burs and rubber points, diamond burs and surface sealant, and abrasive discs, for restoring premolar natural teeth using a commercial composite resin. The surface quality of the restoration resulting from the three techniques was investigated through Ra, Rt, Rp, R, Rk, Rpk, Rvk and RSm roughness parameters, extracted from 3D topography maps. It was found that the use of abrasive discs (G3) promoted better surface quality, with mean Ra roughness near 0.4 μm, against 0.6 μm for the surface sealant group (G2) and 1.0 μm for the rubber points group (G1). It was evidenced that, together with Ra, analyses of roughness parameters regarding the proportion of peaks and valleys, in this case, Rp and Rpk, and roughness spacing, RSm, were significant to gain confidence and reveal reliable screening of the performance between the three techniques, with the best surface condition of the restored area resulting from the use of abrasive discs.