Adequate Surface Preparation Research Articles

Clinical considerations in the application of direct composite for tooth wear.

Various techniques are available for the application of composite to restore worn teeth. Different techniques may be chosen based on the clinical presentation or clinician preference. However, for composite to be successful, there are numerous factors which must be considered in order to optimise the outcome. Pre-treatment steps, such as isolation for optimal moisture control and adequate surface preparation of the tooth, as well as the post build-up objectives of achieving a stable occlusion, good marginal adaptation and final aesthetics, are discussed in the paper.

Influence of nanostructured alumina coating on the clinical performance of zirconia cantilevered resin-bonded fixed dental prostheses: Up to 3-year results of a prospective, randomized, controlled clinical trial

Statement of problemThe debonding of zirconia cantilevered resin-bonded fixed dental prostheses remains a technical complication because zirconia’s chemical inertness impedes adequate surface preparation for bonding. Limited clinical evidence on the performance of various pretreatment methods for the bonding surface of zirconia resin-bonded fixed dental prostheses is available. PurposeThe present prospective, randomized, controlled clinical trial aimed at evaluating the performance of zirconia resin-bonded fixed dental prostheses prepared with nanostructured alumina coating. Material and methodsThe study adopted a prospective, randomized, controlled, double-blind (patients, operator) design to compare the performance of nanostructured alumina coating with that of conventional airborne-particle abrasion. Twenty-seven healthy patients needing a replacement of a missing maxillary or mandibular central or lateral incisor were screened and rated to be eligible, and 31 zirconia cantilevered resin-bonded fixed dental prostheses were randomly allocated into 1 of 2 groups. The first group (n=15), where the restoration bonding surface was airborne-particle abraded with 50-μm alumina, served as a control group. In the second group (n=16), the restorations were pretreated with nanostructured alumina coating. Treatment and data collection were standardized. The primary outcome evaluated was the survival of the RBFDPs as defined by the restoration not debonding. The Kaplan-Meier analysis of cumulative survival was performed, and nonparametric tests were used to determine patient-specific differences between both study groups (age, sex, restored arch, tooth replaced, bonding surface area) (α=.05). Retainer wing surfaces of debonded resin-bonded fixed dental prostheses were inspected under a scanning electron microscope. ResultsWithin a mean ±standard deviation observation period of 22.4 ±7.7 months (minimum, 8.3; maximum, 37.9 months), 3 debondings occurred, and the survival rate was 90.3%. The survival rate was 93.8% for the nanostructured alumina coating and 86.7% for the control group, with no statistically significant differences (log-rank, P=.54). No patient-specific differences were found between study groups (P>.05). As per the scanning electron micrographs, the majority of the nanostructured alumina-coated surfaces had large areas of nanostructured alumina residue, whereas the airborne-particle abraded surfaces exhibited predominantly adhesive failure with less cement residue. ConclusionsOver a mean observation period of 2 years, both zirconia pretreatments showed promising and comparable clinical results; therefore, nanostructured alumina coating could be regarded as a viable alternative pretreatment method to airborne-particle abrasion.

Adhesive Bonding of Copper Prepared by Laser-Interference near the Interference Structuring Limits.

Adhesive bonding requires adequate surface preparation for ensuring an appropriate joint quality. The interest in adhesive joining has recently expanded to thermal systems having a large number of joints employed for manufacturing and assembly. This study presents surface topology of copper 110 produced by a laser-interference setup that would theoretically yield a periodicity of 1.7 μm, which is near the 1.6–2 μm structuring limit that was estimated based on thermal diffusion length scale for an 8 ns laser pulse. The results show that although the expected periodic interference structuring was not attained, the melt-induced texturing was affected by the laser-interference profile. Single-lap shear tests were performed with specimen surfaces prepared by traditional abrasion and laser-interference structuring methods. Several laser processing parameters, such as the laser spot size, density, number of pulses, and raster speed, were studied. Scanning electron microscope and profilometry measurements were used to characterize the processed surface microstructures. Web-like structures, which indicate widespread melting, were shown to be formed at different processing conditions. Based on the surface topologies investigated, two laser raster speeds were selected to make single-lap-joint specimens. Baseline joints were prepared by abrading joining specimens. The shear-lap strength and displacement at maximum load were shown to be higher by 16.8% and 43.8% for the laser-structured specimens than those of the baseline specimens, respectively. Moreover, the load-displacement curves indicated that the laser-structured joints were more ductile than those without laser-structuring. The increased ductility for the laser-structured joints was found to yield an increase in the energy absorbed during shear-lap testing of approximately of 80–90% over those measured for baseline joints. It is another indicator that laser-interference structuring enhanced the bonding performance of single-lap shear joints.

GaN MOS Structures with Low Interface Trap Density

GaN based electronic devices have gained great success in the arena of high-frequency and high-power applications. A high-quality GaN MOS structure has the potential to enable new device designs and higher device performance, thereby bringing the success of GaN electronics to a new level. This paper discusses results of the work on GaN MOS structures show that with adequate surface preparation samples featuring interface trap density down to the ~ 1010 eV-1cm-2 range can be formed.

Effect of surface preparation on corrosion of steel rebars coated with cement-polymer-composites (CPC) and embedded in concrete

Nowadays, Cement-Polymer-Composites are widely used to coat steel rebars to delay the initiation of corrosion in reinforced concrete (RC) structures. However, Cement-Polymer-Composite (CPC) coating is sometimes inadequately applied on rusted steel and can lead to premature under film/crevice corrosion. This paper investigates the effect of such inadequate applications of CPC coating and premature corrosion on the service life of RC structures. For this, maximum surface chloride concentrations, diffusion coefficients, and chloride thresholds were determined by a one-year-long laboratory study on the specimens obtained from a 6-year-old bridge and prepared in the laboratory. Studies found that the chloride threshold of inadequately coated steel rebar (i.e., coating on ‘as received’ surface) is significantly lower than that of the adequately coated steel rebars (i.e., coating on ‘sandblasted’ surface). Also, the corrosion initiation time for systems with inadequately coated steel rebar was about 50% less than that of the systems with adequately coated steel rebars. The corrosion mechanisms were justified with micrographs. It is recommended not to use CPC coated steel rebars if adequate surface preparation (say, cleaning/sandblasting) is not implemented.

Effect of hygrothermal conditioning on the energy release rate and failure mechanism of metal only adherend-glass fibre prepreg co-cured single lap joints

Fibre-reinforced composite materials are extensively used in repair and rehabilitation of oil and gas metal infrastructures which are largely exposed to water and hydrocarbon. An important aspect to this is applying adequate surface preparation to the metal to ensure a durable bond between the composite and metal substrate. In this paper, mild steel surface was prepared using grit blasting and single lap joint (SLJ) test specimens were manufactured and tested to investigate the adhesion in terms of total energy release rate (GT) of the interface between mild steel adherend and glass fibre prepreg. An out-of-water usable epoxy resin primer was incorporated to join mild steel adherend with glass fibre prepreg by curing at a temperature of 55 °C for 48 h. Upon durability testing of the SLJ specimens using hygrothermal conditioning at a temperature of 55 °C for 1000 h, the experimental GT values were seen to reduce significantly. Comparatively lower amount of cohesive failure and increased amount of swelling or delamination of the adhesive was observed for conditioned SLJ specimens when compared to controlled SLJ specimens. Furthermore, the experimental GT values were found to correlate well with an analytical adhesive interface model.

(Invited) Electrochemical Synthesis of High Strength Regular Metal Foams and 3D Micro-Lattices

Three-dimensional metal micro- and nanostructures offer opportunities to develop multifunctional materials with unique combinations of material properties. Traditional strategies to improve the mechanical properties of materials consist of altering either the microstructure or the composition. Both strategies, albeit successful, tend to be rather incremental. The third approach is that of controlling not only the microstructure but also the architecture1. By combining the effect of the architecture with the effect of the microstructure, architectured cellular materials with enhanced mechanical properties are achieved. Modern templating techniques, including colloidal crystal lithography2 and 3D laser lithography3, enable the creation of structures with well-defined sub-micron features. Used in combination with electrochemical routes, the deposition of nickel or copper micro-architectures is achieved with fine control of the microstructure and dimensions. Although electrodeposition is a well-established technique, metal electroforming of cellular micro-materials is demanding. Specific challenges include the electrodeposition onto non-conductive surfaces, adequate surface preparation, appropriate throwing power for electrolyte infiltration into submicron features or proper process optimization. The present talk will cover our recent research activities on the fabrication of nickel and copper regular foams and micro-lattices synthesized by electrochemical processes aiming at achieving high strength and low density materials. Regular porous metal structures are produced by colloidal crystal templating of polystyrene (PS) microspheres. The PS templates are formed by sedimentation of PS microspheres. Under gravity and drying, the PS microspheres form a self-assembled multilayer with a face-centered cubic structure. The templating step is followed by either metal electrodeposition to obtain a metal inverse opal (Figure 1.a) or by electroless deposition of NiB to form a hollow-shell opal (Figure 1.b). The metallic micro-lattices (Figure 1.c) were fabricated by electroless deposition of NiB onto a surface-modified polymer template produced by 3D laser lithography. In situ micromechanical testing of these micro-architectures showed enhanced mechanical properties despite being low density. Increasing the metal coating in micro-lattices from 10 nm to 100 nm improve the mechanical performances by a factor of 3.5 while the density is only multiplied by 2.3.

The effect of materials and surface preparation on joining methods: A review

Materials have been the primary element of the structural community from the existence of ceramics to the more durable and efficient polymers. The uniqueness of these materials stems from a necessity of a particular era. Because of the uniqueness of each material, the study of damage is of key interest in materials research. In conjunction with the essential materials, proper joining techniques are also fundamental in infrastructure; however, joints represent one of the greatest challenges in the design of structures. Current forms of joining include mechanical and adhesive, where adhesive bonding is preferred. However, no joint can be properly designed without adequate surface preparation. Proper methods for surface preparation and joining techniques will be reviewed for composite materials. This review will highlight some of the common approaches used to enhance the strength of the joint and, therefore, the structure itself.

Surface electronic structure for various surface preparations of Nb-doped SrTiO3 (001)

High-resolution angle-resolved photoemission spectroscopy (ARPES) was used to study the surface electronic structure of Nb-doped SrTiO3 (STO) single crystals prepared using a variety of surface preparations. ARPES measurements show that simple degreasing with subsequent anneal in vacuum is not an adequate surface preparation of STO, rather, preparations consisting of etching with buffered HF or HCl, and to a lesser extent, simple water leaching resulted in surfaces with much less disorder. A non-dispersing, mid-gap state was found ∼800 meV above the top of the valence band for samples which underwent etching. This mid-gap state is not present for vacuum-annealed and water-leached samples, as well as for STO thin films grown using molecular beam epitaxy. Theoretical modeling using density functional theory suggests that this mid-gap state is not related to the SrO- and TiO2-terminated surfaces, but rather, is due to a partial hydrogenation of the STO surface that occurs during etching.

Volunteer Revegetation of Waste Rock Surfaces at the Bingham Canyon Mine, Utah

Voluntary recolonization of sulfide-bearing waste rock dumps by native vegetation is inhibited by the harsh chemical and physical conditions. The success of volunteer vegetation on the waste rock surfaces at the Bingham Canyon (Utah) porphyry copper deposit is most strongly dependent on the soil pH and salinity, and to a lesser extent on physical characteristics such as compaction and distance from seed source. Vegetation cover and richness both decline below a paste pH of about 6 and above a paste conductivity of about 0.7 dS/m (for a 1:1 soil to water mixture). No significant vegetation establishment occurs below a soil pH of about 4.5. Young sulfide-bearing waste rock surfaces at Bingham Canyon have high salinity, but as reactive pyrite is depleted and salts are flushed from the soil, the salinity eventually declines, allowing volunteer native vegetation to become established on surfaces with a circumneutral pH. Under natural conditions, the pH of older acidic weathered surfaces will recover very slowly, but it can be rapidly raised by adding relatively small amounts of limestone because there are few intact reactive sulfides. For uncompacted waste rock surfaces with favorable chemical conditions, less than 90% gravel content, and that are located near a native seed source, the arithmetic mean volunteer vegetation cover was 56 +/- 24% and the mean species richness was 17 +/- 5. These data indicate that with adequate surface preparation and limestone addition, direct planting of older, acidic, but low salinity waste rock surfaces can greatly accelerate natural revegetation.

RESIN BOND TO DENTAL CERAMICS, PART II: HIGH‐STRENGTH CERAMICS

The popularity of high‐strength ceramic systems is increasing, and the range of their clinical indications is expanding constantly. Glass‐infiltrated aluminum oxide ceramic (eg, InCeram® Alumina, Vita Zahnfabrik, Bad Säckingen, Germany), densely sintered aluminum oxide ceramic (eg, Procera® AllCeram, Nobel Biocare AB, Gothenburg, Sweden), and zirconium oxide ceramic (eg, Procera AllZirkon®, Lava® 3M ESPE, St. Paul, MN, USA, Cercon®, Dentsply Ceramco, Burlington, NJ, USA) are popular oxide‐based high‐strength ceramic materials that offer favorable esthetic characteristics, mechanical properties, and biocompatibility. Proper selection and application of luting agents for final cementation of all‐ceramic restorations are keys for their clinical success. The few clinical trials on full‐coverage, high‐strength ceramic restorations report acceptable success rates with conventional luting agents. However, an article discussed in Part I of this Critical Appraisal reviewed available in vitro and in vivo studies on this topic and recommended adhesive cementation of ceramic and even high‐strength ceramic restorations. These findings contradict many manufacturers’claims and clinicians’preferences because resin bonding is a technique‐sensitive and time‐consuming procedure. However, resin bonding has a number of advantages (eg, increased retention, improved marginal adaptation, and higher fracture resistance of the restored tooth and the restoration itself) and is required for some minimally invasive treatment options, such as resin‐bonded fixed partial dentures and laminate veneers.The resin bond to silica‐based ceramics is well documented (as discussed in Part I of this Critical Appraisal) and yields predictable and long‐term durable results through adequate surface preparation. Part II focuses on in vitro studies of the bonding interface of some popular high‐strength ceramic materials. Comparative clinical trials are lacking, and the few available in vitro studies indicate that the composition and physical properties of oxide‐based high‐strength ceramics require surface preparation and bonding techniques that differ substantially from those used for silica‐based ceramics.

Shear bond strength of resin composite veneering material to gold alloy with varying metal surface preparations

Statement of Problem. Although adequate surface preparation is indispensable to achieve a consistent and durable bond between resin composite materials and the metal substructures of veneered restorations, information on the bonding performance of current metal adhesive systems is limited. Purpose. The purpose of this study was to evaluate the surface preparation effects of 4 metal conditioners and 1 adhesive system on bonding between a prosthetic resin composite veneering material and a gold casting alloy. Material and Methods. Four primers containing sulfur derivative monomer and designed for conditioning noble metal alloys (Alloy Primer, Infis Opaque Primer, Metal Primer II, and Metaltite) and a surface modification technique (Siloc) were assessed. Cast disk specimens made of gold alloy (Pontor LFC) were either primed with 1 of the 4 primers or treated with the Siloc system and bonded with a light-activated prosthetic resin composite material (New Metacolor Infis). Control specimens were also prepared without the use of a bonding agent. Shear bond strengths were determined before and after thermocycling (20,000 cycles) for evaluation of bond durability. Results. All of the primed and Siloc-treated groups showed improved 24-hour shear bond strengths compared with the control group. After thermocycling, the groups either primed with the Metaltite conditioner or treated with the Siloc system exhibited the highest mean shear bond strengths. Conclusion. The Metaltite conditioner and Siloc system each represent a useful method for improving the bond between the gold alloy and resin composite material tested. (J Prosthet Dent 2001;86:315-9.)

Concrete Roughness Characterization Using Laser Profilometry for Fiber-Reinforced Polymer Sheet Application

The failure of a reinforced concrete member strengthened with fiberreinforced polymer (FRP) laminates may be caused by crushing of concrete, rupture of FRP laminates, or delamination of the FRP sheet. Therefore, the effectiveness and failure mode of FRP sheets applied to beams and columns is related to the degree of adhesion of the epoxy to the concrete surface. When a peeling or delamination failure can be avoided, a more effective engagement of the FRP sheet occurs, which results in more efficient use of the material. One of the principal factors affecting the bond behavior between the concrete and epoxy is the roughness of the concrete substrate. To prepare the bond surface, sand blasting or grinding is typically used to roughen the concrete. To that end, a portable device has been developed to measure the roughness of concrete surfaces. This device can be used as a quality-control tool to characterize surface roughness and identify when an adequate surface preparation has been attained. The method uses laser striping and image analysis. The method was tested on six slabs of sandblasted concrete, which were sandblasted to varying degrees of surface roughness, and a series of nine plastic model concrete surface profiles.

Characterization of porous silicon by NRA, RBS and channeling

Porous silicon could be an interesting material for microelectronic applications if the quality of porous films is significantly improved. This material has the ability to be easily oxidized at relatively low temperatures (< 850° C). Moreover, it preserves the single-crystal characteristics of the substrate, allowing epitaxial growth of Si and GaAs at moderate temperatures. The aim of this work was to determine the impurity content of porous films and to test their crystalline quality, as a function of preparation conditions, using ion beam analysis: NRA, ERDA, RBS and channeling. Relatively good channeling was observed in some porous materials (Xmin = 15%) in spite of the adsorbed impurities and the disorder due to the enormous surface area of the pores: 400 times higher than the geometrical surface area for a 2 μm thick porous layer. The surface density of the impurities is relatively low and can be decreased significantly by adequate surface preparation. Typical results are: 0.6 × 1015 O-at./cm2, 3 × 1015 C-at./cm2, 1015 H-at./cm2 and 0.1 × 1015 F-at./cm2.

Structural applications of adhesives in civil engineering

AbstractThe use of adhesives in civil engineering is reviewed by considering typical applications and experience gained, together with some results of research. The properties and requirements of structural adhesives as used to bond construction materials are discussed briefly. It is concluded that, with an appropriate design of joint, careful selection of a suitable adhesive, and adequate surface preparation, bonded connections may be used in structural applications – at least in the short term. However, caution should be exercised for longer–term applications, particularly if the joint is to be subjected to extreme environmental conditions under sustained load.MST/271

Structural applications of adhesives in civil engineering

The use of adhesives in civil engineering is reviewed by considering typical applications and experience gained, together with some results of research. The properties and requirements of structural adhesives as used to bond construction materials are discussed briefly. It is concluded that, with an appropriate design of joint, careful selection of a suitable adhesive, and adequate surface preparation, bonded connections may be used in structural applications – at least in the short term. However, caution should be exercised for longer–term applications, particularly if the joint is to be subjected to extreme environmental conditions under sustained load.MST/271

MORE METAL LESS PAINT

For many years sprayed metal coatings have been generally regarded as being undercoats for paint systems on iron and steel surfaces, thin coatings of zinc, aluminium or zinc aluminium alloy being applied to increase the adhesion of the paint and to prevent corrosion at the paint/base metal interface. This mode of practice was probably logical when the paint formulations changed to the use of the more resistant resins such as epoxides and before the need for adequate surface preparation was accepted. Sprayed metal coatings have always needed adequate surface preparation as an integral part of their application, so that understandably the good performance in service of such thin metal coatings followed by the application of these resistant paints encouraged the use of cognate coatings, as they represented a measure of insurance against premature failure.

THE PREPARATION OF METALS FOR PROTECTIVE FINISHES

The durability of protective and decorative coatings on metals depends largely on adequate surface preparation or “pretreatment” before the coatings are applied. With some coating processes, e.g. electroplating, inadequate preparation is often immediately noticeable, but in the case of painting some time may elapse before failure takes place and then rectification will probably be expensive and difficult. The lapse of time before failure occurs depends to a large extent on the exposure conditions, and where very severe conditions prevail, as for example on the undersides of ships, complete failure is possible within a few months.