Require Surface Treatment Research Articles

Development of dual-effect AW/Ag/CHI bioactive and antibacterial coating for orthopedic implant surfaces

Titanium implants, which are widely used in orthopedic implant applications, require surface treatments due to their low osteoinduction properties and the risk of postoperative infection. In this study, apatite wollastonite (AW)-based coatings with chitosan (CHI) and silver (Ag) added were applied to the titanium surface using dip coating and drop casting techniques. The obtained coating surfaces were characterized by FESEM, EDS, XRD, FTIR, and TGA–DSC. Biomineralization behaviors were examined by immersing the resulting coatings in simulated body fluid with pH 7.2–7.4. The antibacterial activities of the coatings obtained using S. aureus and E. coli bacterial colonies were examined. Following the successful coating of AW nanoparticles on the Ag and CHI implant substrate, the Ca/P ratio of the coated surface was obtained as 1.4–1.92% after the biomineralization process performed at 37° for 7 days. Ag particles were successfully distributed homogeneously with a 40–50-nm diameter in Ag-doped coatings. It was concluded that the successfully produced composite coating with bioactive and antibacterial properties is a suitable candidate material for metallic implant surfaces.Graphical abstract

Characterization of structural and mechanical properties of DLC films deposited on the surface of minute-scale 3D objects: Changes in the incident behavior of carbon ions

Diamond-like carbon (DLC) films have attracted great interest from the industry because they have beneficial mechanical properties such as low friction, high hardness, and wear resistance. DLC films have been used for the surface modification of various mechanical components, although many components that require surface treatments have complex three-dimensional (3D) surface structures. To date, 3D deposition of DLC films remains difficult using conventional methods. Particularly, uniform deposition technology on 3D components has not been developed for tetrahedral amorphous carbon (ta-C) films, which possess high CC sp3 bonds with high hardness. In this study, the filtered cathodic vacuum arc (FCVA) method was used to synthesize ta-C films on Si substrates placed on the sidewalls of trench-shaped and one-side tilted samples at various tilt angles and investigated their microstructure and hardness by Raman spectroscopy and nanoindentation. The results showed that the G peak position, full width at half maximum of G peak (FWHM (G)), and hardness of the ta-C film on the trench sidewall decreased as the depth from the top surface increased, similar to previous research. In contrast, ta-C films deposited on one-side tilted sample showed little depth dependence, and the film properties were determined by the tilt angle. We revealed that the film property dependence on the trench depth direction is due to the sputtered particles from the opposing trench sidewalls, resulting in graphitization of the film.

Metal‐Organic Chemical Vapor Deposition Grown Low‐Temperature Aluminum Nitride Gate Dielectric for Gallium Nitride on Si High Electron Mobility Transistor

Gate dielectrics for gallium nitride (GaN) high electron mobility transistor (HEMT) technology have always been challenging because of the nonideal semiconductor–dielectric interface, which leads to electronic traps. Plasma‐enhanced chemical vapor deposition and atomic layer deposition are standard techniques, but they require surface treatment and post‐annealing to control these traps. This article explores metal organic chemical vapor deposition‐grown in situ aluminum nitride (AlN) as a gate dielectric. The interface is expected to be pristine as there is no change in the chamber environment. A thin (10 nm) AlN layer is deposited at a low temperature to minimize strain and prevent the formation of an unwanted conductive channel within the device. The electrical and structural properties of this AlN‐capped HEMT are compared to a standard GaN‐capped HEMT, including temperature‐dependent studies. The results show that the AlN‐capped HEMT retains a higher charge in the channel while having an order of magnitude lower gate leakage than the GaN‐capped sample. Furthermore, the AlN‐capped HEMT performs similarly to the GaN‐capped HEMT in terms of temperature‐dependent leakage, dynamic on‐resistance, and temperature coefficient of resistance.

Surface Treatment of Indirect Restorations

Background: All ceramic CAD/CAM materials require surface treatment protocols varying from one type to another according to their chemical composition, including hydrofluoric acid etching, sandblasting, silica coating, laser etching, and non-thermal plasma treatment. This review's objective to analyze and bring up-to-date data about the surface treatment of ceramics.Data: The review just searched electronic publications of papers. Websites "Google Scholar" and "PubMed" were utilized as sources for performing data searches using the following keywords: Surface modification, plasma surface treatment, indirect restoration, ceramics The original papers and clinical investigations that were published between the years 2006 to March 2023 that were the most relevant to the subject at hand were chosen.Conclusion: A variety of surface treatment methods have been proposed to enhance the bonding of restorative materials to resin cement and provide micromechanical retention by altering the restoration's surface mechanically by increasing the degree of roughness or physico/chemically by activating the surface. Hydrophloric acid etch is a golden standard for the surface treatment of feldspathic and lithium disilicate ceramics, the APC concept for zirconia, and hydrofluoric acid or sandblast surface treatment for resin nano-ceramic. A new approach used for surface treatment is plasma treatment, which is really promising in dentistry.

Multi-Inlet Spheroid Generator for High-Throughput Combinatorial Drug Screening Based on the Tumor Microenvironment.

Tumor spheroids are powerful tools for drug screening and understanding tumor physiology. Among spheroid formation methods, the hanging drop method is considered most suitable for high-throughput screening (HTS) of anticancer drugs because it does not require surface treatment. However, it still needs to increase the liquid-holding capacity because hanging drops often fall due to the increased pressure caused by the addition of drugs, cells, etc. Here, we report a multi-inlet spheroid generator (MSG) enabling the stable addition of liquid-containing drugs or cells into a spheroid through its side inlet. The MSG was able to load additional solutions through the side inlet without increasing the force applied to the hanging drop. The volume of the additional liquid was easily controlled by varying the diameter of the side inlet. Furthermore, the sequences of the solution injections were manipulated using multiple side inlets. The feasibility of the MSG in clinical application was demonstrated by testing the efficacy of drugs in patient-derived cancer (PDC) cells and controlling the stromal cell ratio in the tumor microenvironment (TME) containing spheroids. Our results suggest that the MSG is a versatile platform for HTS of anticancer drugs and recapitulating the TME.

In Situ Coatings of Polymeric Films with Core Polystyrene, Core-Shell Polystyrene/SiO2, and Hollow SiO2 Micro/Nanoparticles and Potential Applications.

In many industrial settings, films of polymers such as polypropylene (PP) and polyethylene terephthalate (PET) require surface treatment due to poor wettability and low surface energy. Here, a simple process is presented to prepare durable thin coatings composed of polystyrene (PS) core, PS/SiO2 core-shell, and hollow SiO2 micro/nanoparticles onto PP and PET films as a platform for various potential applications. Corona-treated films were coated with a monolayer of PS microparticles by in situ dispersion polymerization of styrene in ethanol/2-methoxy ethanol with polyvinylpyrrolidone as stabilizer. A similar process on untreated polymeric films did not yield a coating. PS/SiO2 core-shell coated microparticles were produced by in situ polymerization of Si(OEt)4 in ethanol/water onto a PS-coated film, creating a raspberry-like morphology with a hierarchical structure. Hollow porous SiO2-coated microparticles onto a PP/PET film were formed by in situ dissolution of the PS core of the coated PS/SiO2 particles with acetone. The coated films were characterized by E-SEM, FTIR/ATR, and AFM. These coatings may be used as a platform for various applications, e.g. magnetic coatings onto the core PS, superhydrophobic coatings onto the core-shell PS/SiO2, and solidification of oil liquids within the hollow porous SiO2 coating.

Effect of Adhesion Conditions on the Shear Bond Strength of 3D Printing Resins after Thermocycling Used for Definitive Prosthesis.

Three-dimensional (3D) printing polymers such as urethane dimethacrylate (UDMA) and ethoxylated bisphenol A dimethacrylate (Bis-EMA) are typically used in definitive prosthesis and require surface treatments before bonding. However, surface treatment and adhesion conditions often affect long-term use. Herein, polymers were divided into Groups 1 and 2 for the UDMA and Bis-EMA components, respectively. The shear bond strength (SBS) between two types of 3D printing resins and resin cements was measured using Rely X Ultimate Cement and Rely X U200, according to adhesion conditions such as single bond universal (SBU) and airborne-particle abrasion (APA) treatments. Thermocycling was performed to evaluate the long-term stability. Sample surface changes were observed using a scanning electron microscope and surface roughness measuring instrument. The effect of interaction between the resin material and adhesion conditions on the SBS was analyzed via a two-way analysis of variance. The optimal adhesion condition for Group 1 was achieved when U200 was used after APA and SBU, whereas Group 2 was not significantly affected by the adhesion conditions. After thermocycling, the SBS significantly decreased in Group 1 without APA treatment and in the entire Group 2. Additionally, porosity, along with increased roughness, was observed on both material surfaces after APA.

Low temperature, area-selective atomic layer deposition of NiO and Ni

Nickel and nickel oxide are utilized within various device heterostructures for chemical sensing, solar cells, batteries, etc. Recently, the rising interest in realizing low-cost, flexible electronics to enable ubiquitous sensors and solar panels, next-generation displays, and improved human-machine interfaces has driven interest in the development of low-temperature fabrication processes for the integration of inorganic devices with polymeric substrates. Here, we report the low-temperature area-selective atomic layer deposition of Ni by reduction of preformed NiO. Area-selective deposition of NiO is performed at 100 °C using bis(N,N'-di-tert-butylacetamidinato) nickel(II) and water on SiO2 and polystyrene. NiO grows two-dimensionally and without nucleation delay on oxide substrates but not on SiNx or polystyrene, which require surface treatments to promote NiO nucleation. Additionally, prepatterned sp2 carbon-rich resists inhibit the nucleation of NiO, and in this way, carbon-free NiO may be patterned. Subsequent thermal reduction of NiO to Ni was investigated using H2 (50–80 m Torr) and thermally generated H-atoms (3 × 10−5 Torr chamber pressure). Due to the relatively high free surface energy of Ni metal, Ni films undergo dewetting at elevated temperatures when solid-state transport is enabled. Reduction of NiO to Ni is demonstrated at 100 °C and below using atomic hydrogen. In situ x-ray photoelectron spectroscopy is used to determine oxidation state and ex situ x-ray reflectivity and atomic force microscopy are used to probe the film thickness and surface morphology, respectively.

Surface finish of Additively Manufactured Metals: biofilm formation and cellular attachment

Powder bed fusion techniques enable the production of customized and complex devices that meet the requirements of the end user and target application. The medical industry relies on these additive manufacturing technologies for the advantages that these methods offer to accurately fit the patients’ needs. Besides the recent improvements, the production process of 3D printed bespoke implants still requires optimization to achieve the optimal properties that can mimic both the chemical and mechanical characteristics of the anatomical region of interest. In particular, the surface properties of an implant device are crucial to obtain a strong interface and connection with the physiological environment. The layer by layer manufacturing processes lead to the production of complex and high-performance substrates but always require surface treatments during post-processing to improve the implant interaction with the natural tissues and promote a shorter assimilation for the fast recovery and wellness of the patient. Although the surface finishing can be tailored to enhance cells adhesion, proliferation and differentiation in contact with a metal implant, the same surface properties can have a different outcome when dealing with bacteria. This work aims to provide a preliminary analysis on how different post-processing techniques have distinct effects on cells and bacteria colonization of 3D printed titanium implants. The goal of the paper is to highlight the importance of the identification of an optimized methodology for the surface treatment of Ti6Al4V samples produced by Selective Laser Melting (SLM) that improves the implant antimicrobial properties and promotes the osseointegration in a long-term period.

Influence of the surface etching on the corrosion behaviour of a three‐dimensional printed Ti–6Al–4V alloy

AbstractRecently, there has been an extension of three‐dimensional (3D) printing technology of metal materials in the medical field. Additive technology has made it possible to manufacture customized implants. However, 3D printing products often require surface treatment. The possible treatments include acid etching. This study investigated the effect of surface etching on the corrosion resistance of Ti–6Al–4V alloy concerning biological applications. The samples were etched in a mixture of hydrofluoric acid and nitric acid. The corrosion behaviour was described by measuring the time dependence of polarization resistance in a saline solution and surface analysis. The results showed that etching creates a fluoride‐rich layer on the surface, which negatively affects the corrosion behaviour of the material for up to 24 hr. Cytocompatibility tests showed that the resulting layer does not affect the biocompatibility of the material.

Atomic layer deposited aluminum oxide mitigates outgassing from fused filament fabrication–based 3-D printed components

Open-source scientific hardware based on affordable fused filament fabrication (FFF) 3-D printing has the potential to reduce the cost of research tools considerably. So far, development has focused on tools that do not require compatibility with vacuum environments. Highly porous 3-D printed plastics require surface treatments to mitigate their outgassing, and in this study we explored the outgassing reduction from 3-D printed black-colored acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) using a commercial vacuum sealing resin as well as atomic layer deposited (ALD) aluminum oxide (AlOx). The outgassing properties of uncoated plastics could not be measured due to a too high level of outgassing, which was attributed to their high porosity and high specific surface area. However, both the commercial resin and the ALD coatings reduced the extent of outgassing from both ABS and PC, which enabled their comparison by residual gas analysis (RGA). Remarkably, the outgassing performance achieved with ALD AlOx was superior to the performance of the commercial vacuum resin across a temperature range of 40 to 100 °C for both plastics, despite the uneven coverage of the plastic surface with AlOx. Results indicated that both ABS and PC could be made compatible with at least moderate vacuums using ALD AlOx. Thus, the fabrication of laboratory vacuum tools can be realized with affordable 3-D printed plastics. However, further studies on the physical mechanisms behind the outgassing reduction and the durability of the coatings are required.

Silver oxide decomposition mediated direct bonding of silicon-based materials

Silicon-based materials are widely promising electronic components by the combination with metals in power electronics field. However, bonding metal and silicon-based materials generally requires specific surface modification due to their different chemical bonds. Here, we demonstrate a process for directly bonding metals to silicon-based materials that does not require surface treatment, based on the in situ decomposition of Ag2O paste, forming Ag nanoparticles (AgNPs). We demonstrate sound joints of Ag/silicon-based materials at 300–500 °C with the formation of a silicon oxide interlayer containing AgNPs. We propose that Ag in the interlayer attracted other Ag particles to the interface, playing a unique role in this direct bonding process. This process is suitable for various bonding applications in electronics, as well the fabrication of conducting paths for photovoltaic and other applications.

Mechanistic Study of Zr Based Nano-Anti-Corrosion Surface Pretreatment

Most metals used in manufacturing require surface treatment for essential functionalities, including: corrosion resistance, paint adhesion, surface appearance, and/or tactile finishing. Chemical conversion coating is one of the surface treatment methods that provides anti-corrosion properties, and widely used in automobile and other industries. Here we investigated an environmentally friendly chemical conversion method, Zr-based, dilute hexafluorozirconic acid (H2ZrF6) treatment. This method attracted attention because it is phosphate-free and easy to apply, however without clear reaction mechanism. This study focuses on the elemental distribution of the coatings, the change of element concentration and species during the immersion treatment using in situ synchrotron X-ray fluorescence microscopy (XRF) and X-ray Absorption Spectroscopy (XAS). Also, we treated the sample in the solution at certain temperature and time range. Scanning electron microscopy (SEM) and focus ion beam (FIB)-SEM were also used to see the surface and cross-section morphology change before and after the surface treatment. Then by comparing the coating thickness, surface cluster density and cluster size to seek the kinetics of coating formation process. As such, we could determine the mechanism of the coating formation via surface chemical conversion. Figure 1

Experimental Implementation of a New Composite Fabrication Method: Exposing Bare Fibers on the Composite Surface by the Soft Layer Method.

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional component that should have high electrical conductivity, high mechanical properties, and high productivity. In this regard, a carbon fiber/epoxy resin composite can be an ideal material to replace the conventional graphite bipolar plate, which often leads to the catastrophic failure of the entire system because of its inherent brittleness. Though the carbon/epoxy composite has high mechanical properties and is easy to manufacture, the electrical conductivity in the through-thickness direction is poor because of the resin-rich layer that forms on its surface. Therefore, an expanded graphite coating was adopted to solve the electrical conductivity issue. However, the expanded graphite coating not only increases the manufacturing costs but also has poor mechanical properties. In this study, a method to expose fibers on the composite surface is demonstrated. There are currently many methods that can expose fibers by surface treatment after the fabrication of the composite. This new method, however, does not require surface treatment because the fibers are exposed during the manufacture of the composite. By exposing bare carbon fibers on the surface, the electrical conductivity and mechanical strength of the composite are increased drastically.

Experimental Studies on Dry Sliding Wear Behavior of Air Plasma Sprayed Coatings on 410 Steel

Many industrial applications require surface treatments of engineering materials to improve the service life of the components. Thermal spraying is one of the advanced surface treatments adopted for surface coating. In the present study, Cr2O3 powder particles of average particle size 50µm were made to deposit on grit blast 410 steel using air plasma spray technique. Ni/Cr was primarily coated on steel substrates as the bond coat to maintain good bonding between coating and substrate. Dry sliding wear studies were carried out using pin-on-disc Tribometer at room temperature for different sliding velocity at constant load and sliding distance as per ASTM G99 standard. Vickers micro hardness and coating porosity were tested and reported. Surface morphologies and chemical composition of developed coatings were observed and analyzed using scanning electron microscope (SEM) and EDX. The experimental results confirm that, Cr2O3 coating improves the wear resistance and hardness as compared to un-coated substrates.

Effect of enzyme and plasma treatments of bark cloth from Ficus natalensis: morphology and thermal behavior

Bark cloth fabric has been in production in Uganda since the thirteenth century. In a move to preserve its cultural heritage, the United Nations Educational, Scientific and Cultural Organization (UNESCO) proclaimed in 2005 that Ugandan bark cloth is a “Masterpiece of the Oral and Intangible Heritage of Humanity.” Plant fibers require surface treatment before aimed at impurity reduction and for enhancement of fiber to matrix adhesion in composites. An exploratory investigation of enzymatic and plasma treatment of bark cloth is reported. The morphology of the fabric was investigated using scanning electron microscope. Thermal behavior of the fabric was studied using thermogravimetric analysis and differential scanning calorimetry. Fourier transform infrared spectroscopy and ultraviolet–visible (UV–vis) spectrophotometer were used to evaluate the surface functional groups. Enzyme-treated fabrics were cleaner and thermally stable compared to plasma and untreated fabrics.

Micelle-templated composite quantum dots for super-resolution imaging

Quantum dots (QDs) have tremendous potential for biomedical imaging, including super-resolution techniques that permit imaging below the diffraction limit. However, most QDs are produced via organic methods, and hence require surface treatment to render them water-soluble for biological applications. Previously, we reported a micelle-templating method that yields nanocomposites containing multiple core/shell ZnS–CdSe QDs within the same nanocarrier, increasing overall particle brightness and virtually eliminating QD blinking. Here, this technique is extended to the encapsulation of Mn-doped ZnSe QDs (Mn–ZnSe QDs), which have potential applications in super-resolution imaging as a result of the introduction of Mn2+ dopant energy levels. The size, shape and fluorescence characteristics of these doped QD-micelles were compared to those of micelles created using core/shell ZnS–CdSe QDs (ZnS–CdSe QD-micelles). Additionally, the stability of both types of particles to photo-oxidation was investigated. Compared to commercial QDs, micelle-templated QDs demonstrated superior fluorescence intensity, higher signal-to-noise ratios, and greater stability against photo-oxidization,while reducing blinking. Additionally, the fluorescence of doped QD-micelles could be modulated from a bright ‘on’ state to a dark ‘off’ state, with a modulation depth of up to 76%, suggesting the potential of doped QD-micelles for applications in super-resolution imaging.

Influence of surface treatment of yttrium-stabilized tetragonal zirconium oxides and cement type on crown retention after artificial aging

Information about the influence of zirconia crown surface treatment and cement type on the retention of zirconia crowns is limited. It is unclear whether zirconia crowns require surface treatment to enhance their retention. The purpose of this in vitro study was to evaluate the effect of surface treatment on the retention of zirconia crowns cemented with 3 different adhesive resin cements after artificial aging. Ninety extracted human molars were prepared for ceramic crowns (approximately 20-degree taper, approximately 4-mm axial length) and were divided into 3 groups (n=30). Computer-aided design and computer-aided manufacturing zirconia copings were fabricated. Three surface treatments were applied to the intaglio surface of the copings. The control group received no treatment, the second group was airborne-particle abraded with 50 μm Al2O3, and the third group was treated with 30 μm silica-modified Al2O3, The copings were luted with a self-etch (RelyX Unicem 2), a total-etch (Duo-Link), or a self-etch primer (Panavia F 2.0) adhesive cement. They were stored for 24 hours at 37°C before being artificially aged with 5000 (5°C-55°C) thermal cycles and 100,000 cycles of 70 N dynamic loading. Retention was measured on a universal testing machine under tension, with a crosshead speed of 0.5 mm/min. Statistical analysis was performed with 1-way and 2-way ANOVA. Mean retention values ranged from 0.72 to 3.7 MPa. Surface treatment increased crown retention, but the difference was not statistically significant (P>.05), except for the Duo-Link cement group (P<.05). Analysis of the adhesives revealed that the Duo-Link cement resulted in significantly lower crown retention (P<.05) than the other 2 cements. For zirconia crowns, retention seems to be dependent on cement type rather than surface treatment.

AZ31 마그네슘 합금의 플라즈마 전해 산화에서 Sodium Aluminate 농도가 산화막 특성에 미치는 영향

Abstract Magnesium alloy have good physical properties such as good castability, good vibration absorption,high strength/weight ratios. Despite the desirable properties, the poor resistance of Mg alloy impedes their use inmany various applications. Therefore, magnesium alloy require surface treatment to improve hardness, corrosionand wear resistance. Plasma Electrolytic Oxidation (PEO) is one the surface treatment methods to form oxidelayer on Mg alloy in alkali electrolyte. In comparison with Anodizing, there is environmental process having higherhardness and faster deposition rate. In this study, the characteristies of oxide film were examined after coating theAZ31 Mg alloy through the PEO process. We changed concentration of sodium aluminate into K 2 ZrF 6 , KF baseelectrolyte. The morphologies of the coating layer were characterized by using scanning electron microscopy(SEM). Corrosion resistance also investigated by potentiodynamic polarization analysis. As a result, propertiy ofoxide layer were changed by concentration of sodium aluminate. Increasing with concentration of sodium alumi-nate in electrolyte, the oxidation layer was denser and the pore size was smaller on the surface.(Received July 27, 2012; Revised August 13, 2012; Accepted August 20, 2012)Key words: PEO, Plasma electrolytic oxidation, MAO, Micro arc oxidation, AZ31, Magnesium alloy

Preparation and characterization of spark-anodized Al-alloys: Physical, chemical and tribological properties

Aerospace applications and energy saving strategies in general boosted the interest and the research in the field of light weight materials, typically on alloys based on aluminium. Aluminium itself does not provide sufficient mechanical strength for structural parts, but there exists a lot of recently developed alloys containing silicon, copper, magnesium, zinc or manganese in various combinations and compositions exhibiting excellent mechanical properties. These alloys require surface treatments or coatings to withstand corrosive ambient conditions. Among those treatments known as chromate replacements, plasma oxidation processes were used for different applications, especially if the surfaces have to face mechanical load or severe environmental conditions. In this work, specimens of different aluminium alloys have been plasma oxidized by micro-arc treatment in silicate and phosphate solutions. The ceramic coatings were characterized with respect to phase composition, micro-hardness and corrosion stability. In addition, the tribological performance of the coatings was investigated using a ball-on-disc tribometer with reciprocating motion against sintered alumina ball. The typical worn surfaces of the Al substrate and the ceramic coatings were observed by a scanning electron microscope. Applying same wear conditions, the wear rates in different depth of the coatings are nearly similar. However, in a defined depth of the coatings, wear rate gradually decreases with wear duration. During friction process, a-stable transfer layer consisting of oxides was formed on the tribo-contact area of the coatings. The friction coefficient in a steady friction state is in the range of 0.8.