Surface Preparation Research Articles

Comparative analysis of primers and alternative polypropylene pre-treatment techniques

ABSTRACT The test polypropylene substrates obtained from the original plastic car parts for Škoda Superb were subjected to 10 pre-treatment techniques: solvent cleaning (isopropanol, xylene), mechanical abrasion, immersion in a chromic acid mixture, flame activation, atmospheric and low-pressure plasma treatment, corona discharges and the application of two different primers (also called adhesion promoters). One of the primers, based on chlorinated polypropylene, was commercially available, while the other was prepared in our laboratory using polypropylene grafted with maleic anhydride. The test substrates were characterized using contact angle measurement for designation of surface free energy, Atomic Force Microscope (AFM) for roughness analysis, Scanning Electron Microscopy (SEM) for surface topography, and Energy Dispersive X-ray Spectrometry (EDX) for surface oxygen and contamination analysis. The suitability of the surface preparation methods in the industry was evaluated through peel strength tests (adhesive bonding process) and cross-cut tests (painting process). Not all tested methods were effective in increasing adhesion, especially in the adhesive bonding process, and even fewer in the painting process. However, some of them were suitable for both applications. The use of primers was found to be crucial.

Influence of Surface Preparation on the Microstructure and Mechanical Properties of Cold-Sprayed Nickel Coatings on Al 7075 Alloy

This work presents the effect of surface roughness (Al 7075) on the microstructure and mechanical properties of cold-sprayed nickel coatings. Coating analysis included substrate surfaces and coating geometry, microstructure characterization, microhardness, nanohardness, elastic modulus, and adhesion. The results show that the surface preparation had a significant effect on coating adhesion and microstructure. The coating deposited at the highest gas temperature revealed a dense microstructure, showing very good adhesion of the impacting powder particles to the substrate and good bonding between deposited layers. The Ni grains with different shapes (elongated, equiaxed) and sizes of a few dozen to several hundred nanometres were present in the splats. An increase in temperature caused significant growth in coating thickness as a result of the powder grains’ higher velocity. Moreover, higher gas temperature resulted in the enhancement of micro- and nanohardness, elastic modulus, and adhesion. The adhesive bond strength of Ni coatings in the tested temperature ranges from 500 °C to 800 °C increased with the increase in the surface roughness of the substrate. For the Al 7075 coarse grit-blasted (CG) substrate with the highest roughness, the adhesion reached the highest value of 44.6 MPa when the working gas was at a temperature of 800 °C. There were no distinct dependencies of surface roughness and thickness on the mechanical properties of the cold-sprayed nickel coating.

Preparation of wettability-controlled surface by electrostatic spray deposition to improve performance uniformity of small molecule/polymer blend organic field-effect transistors

Preparation of wettability-controlled surface by electrostatic spray deposition to improve performance uniformity of small molecule/polymer blend organic field-effect transistors

Nickel electroplating of 6061-T6 aluminum alloy using anodizing process as the pretreatment

Typically, aluminum and its alloys fail to be coated by the electroplating process due to the existence of an inherent oxide layer on the surface which reduces the adhesion between the coatings and the substrate. In this regard, suitable surface preparation is required before the electroplating process. In this study, the anodizing process is chosen as the surface pretreatment. For this purpose, the soft anodizing process was done in a 0.3 M oxalic acid electrolyte at 25 °C and 90 V for different duration. AAO dissolving process was performed to increase the diameter of the pores. Finally, electroplating of nickel was performed in a Watts bath at 40 °C, pH of 3, and different current densities. Three variable of anodizing and dissolving durations and electroplating current density were optimized by a response surface methodology to form a continuous layer of electroplated nickel on the surface. FE-SEM surface morphology, SEM cross-sectional observations, surface XRD characteristics and Daimler-Benz adhesion test were performed to characterize and evaluate the coatings. The optimization of the three variables led to a sequence process of a 9 min anodizing treatment, followed by a 100 min dissolving stage, then electroplating under a current density of 20 mA/cm2. The formation mechanism of the electroplated layer is thoroughly discussed.

Assessment of surface irregularities created by controlled liquid droplet on the surface of stainless steel AISI 304L

Surfaces created by the erosive action of water droplets have not been sufficiently explored because of their stochastic structure, which depends on hydraulic parameters. This article details the complex analysis of surfaces created by the controlled distribution of water droplets on the surface of AISI 304L using an ultrasonically stimulated water jet. The traverse speed of the jet controlled the distribution of the water droplets. The surface topology was modified in an interleaved mode when the trajectories were parallel for all samples. Additionally, the second layer treated the other half of the preprepared samples with a perpendicular trajectory with respect to the parallel trajectory. The 3D surface reconstruction was performed using a noncontact MicroProf FRT measuring instrument. Several profile roughness parameters (Ra, Rz, Rv, Rp, Rsk, and Rku), areal surface roughness parameters (Sa, Sz, Sp, Sv, Ssk, Sku, Sdr, Sk, Spk, and Svk) and surface isotropy values were measured for the surfaces generated using variations in the traverse speed of the jet. The measurement results show a decreasing trend of surface roughness upon an increase in the traverse speed, and a better surface finish was also measured for the cross-hatch trajectory compared to the linear trajectory. The results also show that the generated surfaces have deeper valleys with truncated peaks, which are suitable for use in a wide range of technical and medical applications. This study shows the potential utilization of controlled liquid droplet impingement for surface preparation in various application domains.

Comparison Between Chlorhexidine Gluconate and Povidone Iodine In Preventing Surgical Site Infection In Laparoscopic Cholecystectomy

Surgical site infection is one of the major postoperative complication resulting in an increase in both morbidity and mortality of the patient. Preoperative patients body surface preparation is one of the major factors in preventing surgical site infection. In this study we compared povidone iodine usually used disinfectant with chlorhexidine gluconate for surgical site infection
 MATERIALS & METHODS
 It was a cross sectional study conducted at General Surgery ward Gulab Devi Hospital Lahore from January 2021 to December 2022. A total of 200 patients undergoing laparoscopic cholecystectomy were included in this study through purposive sampling and then divided into two groups using lottery methods. In Group A peroperative patients skin preparation was done with 10% povidone iodine while in Group B 4% chlorhexidine gluconate was used for skin preparation. Patients with empyema gall bladder, gall bladder or gut perforation and laparoscopic procedures converted to open were excluded from this study.
 RESULTS
 In this study mean age of 45.8 ± 10.3 years with range from 25 to 65 years. In Group A mean age was 45.7 ± 10.8 years while in group B it was 45.8 ± 9.8 years. In Group A 12% wound infection was documented while in Group B it was only 4% (P-value 0.03).
 CONCLUSION
 Many antiseptic solutions are used for patient skin preparation before surgery which includes chlorhexidine gluconate, povidone iodine and alcohol. Among these solutions povidone iodine solution is commonly used. In our study we compared povidone iodine with chlorhexidine gluconate solution which showed less surgical site infection which shows chlorhexidine gluconate solution can be safely replaced with povidone iodine solution for skin preparation.

Facile Preparation of Hydrogel-Coated Surfaces with Antifouling and Salt Resistance for Efficient Solar-Driven Water Evaporation.

Hydrogel-based evaporators are a promising strategy to obtain freshwater from seawater and sewage. However, the time-consuming and energy-consuming methods used in hydrogel preparation, as well as their limited scalability, are major factors that hinder the development of a hydrogel-based evaporator. Herein, a facile and scalable strategy was designed to prepare a hydrogel-coated evaporator to realize efficient solar-driven water evaporation. The hydrogel coating layer is composed of a robust 3D network formed by tannic acid (TA) and poly(vinyl alcohol) (PVA) through a hydrogen bond. With the assistance of TA surface modifier, carbon black (CB) is uniformly distributed within the hydrogel matrix, endowing the coating with remarkable photothermal properties. In addition, Fe3+ is deposited on the surface of the hydrogel coating through metal coordination with TA, further improving the light absorption of the coating. Due to the synergistic effect of CB and Fe3+, the hydrogel-coated foam exhibited excellent photothermal properties. The water evaporation rate reached 3.64 kg m-2 h-1 under 1 sun irradiation. Because of the hydration ability of PVA hydrogel and the large porous structure of the foam, the hydrogel-coated foam demonstrated excellent antifouling performance and salt resistance. This study provides a facile method for designing and manufacturing high-performance solar-driven water evaporation materials.

Thermal stability, work function and Fermi level analysis of 2D multi-layered hexagonal boron nitride films

Thermal stability and Fermi level analysis of commercial multilayer (ML) and as-grown 10 nm thick hexagonal boron nitride (hBN) films on Cu foil by atmospheric chemical vapor deposition (APCVD) by heating in N2 and air at temperatures ≤900 °C are studied. For all samples, progressive surface oxidation was observed correlating with higher hBN nucleation density. Thermal stability was measured in air from 200 °C to 400 °C (relative humidity ∼65%) where commercial ML and APCVD material degraded; BN peaks begin to be replaced by BO peaks at temperatures >300 °C. It is shown that hBN thermal stability is sensitive to Tgrowth and Cu foil surface preparation methods such as electropolishing (EP). We evaluate as-grown material for different Tgrowth conditions (1000 °C, 1030 °C, 1050 °C and 1060 °C) by ultraviolet photoelectron spectroscopy (UPS) to locate and understand subsequent Fermi level and work function variation, confirming our material is in general n-type, which becomes increasingly so as thermal stability regresses. To this effect, we observe a work function increase of 0.45 eV as BO increases with in-situ anneal temperature. An average electron affinity of 2.13 eV and 1.7 eV is determined for commercial hBN and APCVD material, respectively. Further work is required by material scientists to optimize the material properties of CVD hBN.

Shear Bond Strength of Metal and Ceramic Brackets Depending on Etching Protocol in Direct Bonding Technique.

Successful orthodontic therapy, apart from a proper treatment plan, depends on optimal bracket-enamel adhesion. Among numerous factors affecting adhesion, the type of bracket and preparation of the tooth's surface are crucial. The aim of this study was to compare the shear bond strength (SBS) of metal and ceramic brackets to the enamel's surface using direct bonding. Forty extracted human premolars were divided into four groups according to the etching method (etch-and-rinse and self-etch) and bracket type. The SBS and adhesive remnant index (ARI) were determined. The ceramic brackets achieved the highest SBS values both in the self-etch (SE) and etch-and-rinse (ER) protocols. Higher SBS values for ceramic and metallic brackets were found in the ER protocol. In all tested groups, the achieved SBS value was satisfactory to withstand orthodontic and occlusal forces. There was no significant difference in the ARI score between study groups (p = 0.71). The fracture occurred between the bracket base and adhesive material in both types of brackets, which decreased the risk of enamel damage during debonding.

The effect of different enamel surface preparations on microleakage under orthodontic brackets

Microleakage is caused by many factors, including polymerization shrinkage of the resin, thermal expansion differences between the enamel and the adhesive, and inadequate adherence. This study aims to assess the microleakage value under orthodontic brackets after three distinct enamel surface preparations and compare the results to the traditional procedure. Fifty-four intact upper premolars were randomly distributed into three groups. First group 18 teeth etched with 36% phosphoric acid Dentsply. Second group 18 teeth etched with %1.23 acidulated phosphate fluoride (APF) incorporated phosphoric acid 25%APF 75%phosphoric acid Dentsply. Third group 18 teeth etched with Trans Bond TM Plus Self-Etching prime 3M Unitek, Monrovia, USA. Then, according to the manufacturer's instructions, all groups bonded to stainless steel brackets RAZOR, IOS, USA, using light-cured composite 3M Unitek/ Monrovia, USA. Then, each subgroup was divided into 3 subgroups, 6 teeth each. The first subgroup thermocycled 500 cycles between 5 C and 55 UC in deionized water and tested after 24 hours of water storage. The second subgroup was also thermocycled and tested after 2 months of water storage. The third subgroup was subjected to cyclic acid attack for 2 months by an acidic solution pH=2.5. Microleakage was evaluated using a dye penetration technique. All samples are sectioned and evaluated under a stereomicroscope. For statistical analysis, the Kruskal-Wallis test was employed. P=0.05 was the level of significance. A significant difference was between etching groups following a thermocycler and a twenty-four-hour water storage, no significant difference after thermocycling and two months of water storage, and significant difference at the occlusal side and between overall means of compared etching groups. This study revealed that the highest microleakage values were in the SEP self-etch prime group, then EF 1.23% APF incorporated phosphoric acid group and the ER 36% phosphoric acid group. The gingival side had more microleakage than the occlusal side. Adding around 20-25 percent of 1.23 percent of phosphoric acid for enamel preparation before orthodontic bonding increases microleakage values, but SEP remains the highest. Keywords: Microleakage, Self-etch prime, Acidulated phosphate fluoride, Stainless steel brackets

Evaluation of the Influence of Acid Etching Technique on Surface Roughness and Fracture Strength of Heat-Pressed Lithium-disilicate Veneers

Abstract Background Metal-free ceramic veneers exhibit many desirable properties. However, low fracture strength is a major disadvantage. The success of the veneers depends on optimal tooth preparation and intaglio surface preparation techniques for bonding porcelain substrates to the tooth to ensure clinical success. This study was conducted to evaluate the influence of acid etching technique on surface roughness and fracture strength of veneers. Methods The in vitro study was conducted on maxillary central incisors that were prepared to receive the veneers; the specimens were divided into two groups—group A and group B. The intaglio surface of veneer in both groups was etched with 4.6 % of the hydrofluoric acid solution for 30 seconds, in group B specimens were further treated with 33% sodium hypochlorite solution treatment following which the surface roughness was measured and calculated with scanning electron microscope at a magnification of 3000X and profilometer, respectively. The fracture strength of the specimens in both groups was determined by subjecting the tooth with veneer to a universal testing machine; the force was applied until the fracture occurred. Results There was a significant difference observed in the surface roughness, fracture strength, and bond strength of the heat-pressed lithium-disilicate veneers treated solely with hydrofluoric acid and samples treated with hydrofluoric acid and phosphoric acid. Conclusion Optimizing porcelain surfaces before treatment with various adhesives and luting resins requires an understanding of the involved substrates and materials, as well as a logical and systematic methodology in their manipulation. The intaglio surface of the veneers treated with hydrofluoric acid followed with phosphoric acid has no significant difference observed in the properties of the veneers but has better bonding with the tooth structure.

Preparation of surface modified nano-hydrotalcite and its applicaiton as a flow improver for crude oil

The poor fluidity of crude oil under low-temperature is one of the key issues affecting crude oil extraction and transportation, which requires a large amount of chemicals or energy. In order to solve this problem, anionic surfactants modified hydrotalcite was prepared in this study, its performance as flow improver was investigated, and the mechanism of improving the flowability of crude oil caused by the interaction between modified hydrotalcite and wax and resin in crude oil was explored. Anionic surfactant modified hydrotalcite has a high viscosity reduction effect on crude oil, and sodium dodecyl sulfate modified hydrotalcite (12S-MNH) has the most significant effect on the viscosity of poplar oil sample (YL). Further research was conducted on the viscosity reducing effect of 12S-MNH can reduce the viscosity of YL crude oil by 96.6% (31 °C) and depress the pour point by 14.0 °C at most. The modification of hydrotalcite was characterized by Fourier Infrared (FTIR), zeta potential particle size analysis, scanning electron microscopy (SEM), thermogravimetric analysis, X-ray diffraction (XRD) and contact angle, which confirms the modification of hydrotalcite by sodium lauryl sulphate can prepare surface hydrophobic nanoparticle with smaller average particle size. Combined with DSC analysis and optical microscopy analysis of oil samples added with 12S-MNH, the mechanism of 12S-MNH on viscosity and pour point of crude oil was discussed.

Preparation of Protein A Membrane Adsorbers Using Strain-Promoted, Copper-Free Dibenzocyclooctyne (DBCO)-Azide Click Chemistry.

Protein A chromatography is the preferred unit operation for purifying Fc-based proteins. Convective chromatography technologies, like membrane adsorbers, can perform the purification rapidly and improve throughput dramatically. While the literature reports the preparation of Protein A membrane adsorbers utilizing traditional coupling chemistries that target lysine or thiol groups on the Protein A ligand, this study demonstrates a new approach utilizing copper-free dibenzocyclooctyne (DBCO)-azide click chemistry. The synthetic pathway consists of three main steps: bioconjugation of Protein A with a DBCO-polyethylene glycol (PEG) linker, preparation of an azide-functionalized membrane surface, and click reaction of DBCO-Protein A onto the membrane surface. Using polyclonal human immunoglobulins (hIgG) as the target molecule, Protein A membranes prepared by this synthetic pathway showed a flowrate-independent dynamic binding capacity of ~10 mg/mL membrane at 10% breakthrough. Fitting of static binding capacity measurements to the Langmuir adsorption isotherm showed a maximum binding (qmax) of 27.48 ± 1.31 mg/mL and an apparent equilibrium dissociation constant (Kd) of value of 1.72 × 10-1 ± 4.03 × 10-2 mg/mL. This work represents a new application for copper-less click chemistry in the membrane chromatography space and outlines a synthetic pathway that can be followed for immobilization of other ligands.

Vibratory polishing effects on passivity of 304L stainless steel surfaces

ABSTRACT Surface spectroscopy analysis and electrochemistry were applied to study the effects of surface preparation by vibratory polishing on the passivity of stainless steel 304L surfaces. Compared to grinding by traditional mechanical polishing, vibratory polishing promotes the enrichment of Cr(III) oxide and hydroxide species in the duplex chemical structure of the surface native oxide film by enhancing selective Fe oxidation and dissolution. As a result, spontaneous passivity, tested in aggressive sulphuric acid electrolyte, is enhanced. However, in the absence of enrichment in Mo(IV) and Mo(VI) species in the passive film, the Cr enrichment does not enhance passivity upon anodic polarisation nor increase the resistance to Cl-induced passivity breakdown and initiation of localised corrosion in accelerated testing conditions. The results provide comprehensive insight into the mechanisms underlying the passivity enhancement of stainless steel by surface engineering.

Wear and corrosion resistance of zinc-oxide and zirconium-oxide coated WE43 magnesium alloy

Magnesium alloy, which draws attention with its lightness and high specific strength, is frequently preferred due to its advantages. However, it is necessary to improve the wear and corrosion properties in order to develop the areas of use in the automotive, aircraft, and space industries. For this purpose, after the surface preparation of the main material WE43 Mg alloy, ZnO and ZrO2 coatings were made and characterized in this study. The surface morphology and structural and chemical properties of the samples were investigated using profilometry, contact angle tests, scanning electron microscopy, and x-ray diffraction. Corrosion tests have been carried out. In order to determine the wear performance of the samples, the wear-related volume losses were measured and the friction coefficients were compared. Layers with 2–6 μm coating thickness were obtained homogeneously on the polished and sandblasted sample surfaces. It was determined that the coating layers grew in the form of columns and did not contain capillary cracks. As a result of the study, it was observed that the ZnO-coated samples had the highest wear and corrosion resistance, and the wear and corrosion resistance of the coatings and magnesium alloy substrates improved.

A novel pathway for joining power plant dissimilar steels by diffusion bonding in as-machined surface condition

Surface preparation, which includes polishing and cleaning, has become a crucial stage in diffusion bonding for creating excellent quality durable joints. Polishing is a time-consuming and labor-intensive task that reduces process productivity. To increase process productivity, the joints must be established under as-machined surface conditions. Pressure impulses were used to conduct diffusion bonding of P92 steel and 316L austenitic stainless steel under as-machined surface conditions. At 1000 °C, 30 min bonding time and 20 MPa Maximum impulse pressure, tensile strength and elongation of the joint was found to be 628.5 MPa and 38.6 % respectively.

Direct writing concave structure on viscoelastic substrate for loading and releasing liquid on skin surface

Droplet deposition on deformable matrix has a broad application prospect. Regular deposition and diffusion of droplet on the substrate is the key to prepare flexible concave structure. Direct writing technique is an advanced method for depositing ink droplet on various substrates, which could produce a variety of deposition forms. Meanwhile, direct writing technique has the characteristics of simplicity, convenience and strong controllability. In this work, patterned concave structure was fabricated with viscoelastic substrate by direct writing technology, depositing behavior of ink droplet, formation condition and shape control of concave structure were studied with viscoelastic substrate, and practical application of the patterned concave structure was explored in loading and releasing liquid on skin surface. This study provides an efficient method for the preparation and application of controllable concave surface.

Screw Only Fixation vs Plate Fixation For 1st MTPJ Arthrodesis: A Comparative Retrospective Study

Category: Midfoot/Forefoot; Other Introduction/Purpose: First metatarsolphalangeal joint (MTPJ) arthrodesis is a commonly performed surgical procedure for end- stage arthritis. Various fixation techniques have been described. The most commonly used are screw-only fixation (either crossed or parallel) or plate fixation (with or without independent lag-screws). A recent systematic review reported that union rates for screw fixation were lower compared to plate constructs. The aim of this study was to compare union rates, complication rates and functional outcomes between screw-only fixation and plate fixation in a recent cohort of patients undergoing first MTPJ arthrodesis at a tertiary foot ankle orthopaedic institution. Methods: This was a retrospective cohort study. After institutional review board approval, a database search was conducted to identify patients who underwent primary first MTPJ arthrodesis between 2015 and 2022. All patients had a dorsal approach, preparation of joint surfaces with cup and cone reamers and fixation with either crossed cannulated screws or a dorsal pre- contoured locking plate (with or without an independent lag-screw). Demographic, operative (fixation type) and outcome data was collected. The primary outcome was the incidence of arthrodesis at 6 months postoperatively. Secondary outcomes included complications at 6 months postoperatively and change in functional outcome scores from preoperatively to 6 months postoperatively as assessed by the Functional Ankle Ability Measure (FAAM) and Visual Analog Pain scores (VAS). Statistical analyses included descriptive statistics as well as univariable and multivariable analyses to determine if one fixation method was associated with a higher incidence of arthrodesis. Results: There were 108 patients identified, 54 in the screw-only group (mean age 62.9 years, 79.6% female, mean body-mass index (BMI) 28.6 kg/m2) and 54 in the plate-fixation group (mean age 63.2 years, 81.5% female, mean BMI 30.0kg/m2). Arthrodesis at 6 months in the screw-only group occurred in 52 of 54 patients (96.3%) and in 50 of 54 patients (92.6%) in the plate-fixation group, p=0.68. Fixation type was not a predictor of non-union on multivariable analysis. The complication rate was 11.1% (n=6) in screw-only patients (four hardware removals, two non-unions) and 14.8% (n=8) in plate-fixation patients (four non-unions, two hardware removals, two wound infections), p=0.57. Both groups reported increases in VAS and FAAM scores at 6 months from baseline, with no significant between-group differences. Conclusion: The arthrodesis rate for screw-only fixation was higher than patients receiving plate-fixation, however, this difference did not reach statistical significance. Similar complication rates were observed in each group. These results provide evidence for the safety and efficacy of screw-only fixation constructs, however, further adequately powered prospective studies are required. Future studies should also include a cost effectiveness analysis and a comparison of radiation exposure and operative time between groups to determine the optimal fixation method for patients undergoing this procedure.

Effect of Two Different Invasive Tooth Surface Preparation Techniques on Penetration, Marginal Adaptation, and Retention of Pit and Fissure Sealant (An In Vitro Study)

Effect of Two Different Invasive Tooth Surface Preparation Techniques on Penetration, Marginal Adaptation, and Retention of Pit and Fissure Sealant (An In Vitro Study)

The Influence of Surface Preparation on Corrosion-Protection Properties of Oxide Layers Formed on MA8 Magnesium Alloy by Microarc Oxidation

The Influence of Surface Preparation on Corrosion-Protection Properties of Oxide Layers Formed on MA8 Magnesium Alloy by Microarc Oxidation