Surface preparation techniques for biomedical applications

3 - Surface preparation of component materials

Objective: Repair of an indirect restoration is usually preferred over its replacement. This study aimed to evaluate the effect of silane in different surface preparation techniques on the bond strength of direct to indirect composite resin.Methods: For this in vitro experimental study, 48 indirect composite cubes were fabricated, divided into 4 groups of 12 and subjected to the following preparation techniques: Group 1. Sandblasting with 50μaluminum oxide particles (SB), Group 2. Sandblasting+ silanization (SB+Sil), Group 3. Etching with 9.5% hydrofluoric (HF) acid, Group 4. Etching with 9.5% HF acid+ silanization (HF+Sil). Before the restoration process, specimens were subjected to 500 thermal cycles and received surface preparations. Single Bond adhesive was applied to the surface in all groups. Specimens were restored with direct composite resin and stored in an incubator at 37°C for 24h. Fracture was induced in the specimens by an Instron machine and the shear bond strength was measured. Data were converted to mega Pascal and analyzed using two-way ANOVA and Tukey’s post hoc.Results: The highest shear bond strength was 13.85 (2.75) MPa and belonged to group 1; while the lowest bond strength was 8.43 (1.35) MPa and observed in group 2.Conclusion: Based on the obtained results, composite surface preparation by sandblasting yields more favorable results than HF acid etching and application of silane can also increase the bond strength.

Adhesive bonding is a commonly used technique to join different parts or structures. The bonding is attributed surface adhesion. Adhesion is defined by the ASTM [1] as “the state in which two surfaces are held together by interfacial forces which consist of valence force or interlocking action or both.” Both of these are highly dependent on the surface conditions, which makes the surface preparation very critical to the performance of adhesive bonding. Obtaining a strong adhesive bond requires various considerations. Wegman and Levi [2] describe several key steps of adhesive bonding that are summarized here: receiving materials, knowledge of the fabrication process for the parts, mating the parts to be bonded, and surface preparation. Among all these steps, surface preparation is usually the most critical, complex, and frequently neglected step in the bonding sequence. Surface preparation can remove the intermediate surface, paint, rust or oxide layer. Different materials including adherents, adhesives, and chemicals require different surface preparation techniques but in general, the surface preparation needs to consider the cleanliness, roughness, and functionality of the surface.Adhesive bonding techniques specific to Aluminum and Copper are highlighted.

We propose a new method for cleaning blind via holes after laser drilling of PWBs using oxygen plasma treatment. This report dealt with three kinds of PWB materials: epoxy resin and two kinds of aramid fiber reinforced plastics (AFRP: Technora or Kevlar fiber reinforcement). We observed the drilled holes after plasma treatment using both an optical and a scanning electric microscope (SEM). It was confirmed that adequate etching took place in the drilled holes by plasma treatment. We also compared the hole wall and hole bottom after plasma treatment with ones after chemical etching. It was clear that there was no damage to the aramid fiber tip on the hole wall, and that a smooth roughness of the hole wall was obtained by means of plasma treatment. As a result, we demonstrated that the plasma treatment is effective in cleaning the laser drilled holes of PWBs.

Investigation on bonding behavior between CFRP patch and corrosion-damaged steel associated with surface preparation techniques

Background:Porcelain from prosthesis such as crown or bridge can be fractured if exposed to trauma; and, can be repaired at chairside using composite resin.Aim:To investigate the fracture resistance of few techniques of surface preparation in repairing fractured porcelain using composite resin.Materials and Methods:Eighty samples of porcelain blocks were divided into 4 groups for different surface preparations, such as, Cimara repairing kit; porcelain etch kit containing hydrofluoric acid; Panavia F resin cement; and, sandblasting using aluminium oxide, before composite resin (Filtek Z250, 3M ESPE) was bonded to the prepared porcelain blocks. Twenty others samples in the control group comprised of pure porcelain blocks. The fracture resistance of each sample was tested using Instron machine (UK).Results:With the exception of the group repaired using hydrofluoric acid (3.04±1.04 Mpa), all the other groups showed significant difference in the fracture resistance values when compared to the control group (3.05 ± 1.42 MPa) at P<0.05.Conclusions:Etching of the porcelain blocks with hydrofluoric acid holds promise in the repair of fractured porcelain with composite resin at chairside.

This article addresses the problems encountered during surface preparation and surface passivation of the InAs-GaSb strain layer superlattice. An analysis of the surface preparation techniques along with the effect on the performance characteristics for different passivants is presented. The passivants and surface preparation techniques are compared on the basis of their insulation properties, capacitance-voltage (C-V) characteristics, minority carrier lifetime, and 1/f flicker noise characteristics.

In this work, we investigated experimentally the various factors influencing the extraction of indentation stress-strain curves from spherical nanoindentation on metal samples using two different tip radii. In particular, we focused on the effects of (i) the surface preparation techniques used, (ii) the presence of a surface oxide layer, and (iii) the occurrence of pop-ins at the elastic-plastic transition on our newly developed data analysis methods for extracting reliable indentation stress-strain curves. Rough mechanical polishing was shown to introduce a large scatter in the measured indentation yield strengths, whereas electropolishing or vibropolishing produced consistent results reflective of the pristine sample. The data analysis techniques used were able to discard the portions of the raw data affected by a thin oxide layer, present on most metal surfaces, and yield reasonable indentation stress-strain curves. Experiments with different indenter tip radii on annealed and cold-worked samples indicated that pop-ins are caused by delayed nucleation of dislocations in the sample under the indenter.

Effect of surface treatment on photo-electric properties of CZT thick film for radiation detector

In the literature it is a common belief that electropolishing mitigates primary water stress corrosion cracking (PWSCC) because it removes superficial cold work. Here, it is shown that electropolished Alloy 600 (UNS N06600) exposed to hydrogenated steam undergoes internal Cr oxidation, whereas mechanical polishing induces external oxidation. This has implications for SCC initiation, which has been tested with different surface preparations (electropolishing and mechanical polishing) using reverse-U-bend (RUB) and C-ring samples. The results show a systematic trend that mechanically polished surfaces are more resistant to stress corrosion cracking (SCC) than electropolished surfaces. The mechanism involved in this increased resistance is thought to be related to short-circuit diffusion of Cr to the surface, which promotes external rather than internal oxidation. The role of compressive stress induced by mechanical polishing is a less-likely explanation of the observed effects. Mechanical polishing does not suppress PWSCC completely because if the external oxide layer breaks, the exposed material may continue to oxidize internally.

The influence of several surface preparation techniques, such as electropolishing, chemical polishing, anodizing, and firing in an UHV furnace with different cool-down cycles, on Q0 values, peak rf fields, and surface mean free path ls have been studied in a welded S-band cavity having large beam tubes. With special treatments, peak fields up to 810 G at Q0≈1011 have been obtained, whereas the surface mean free paths stayed fairly short (≲300 Å ) not changing systematically with (surface) treatment. Hence, to obtain low rf losses and high rf fields, the purity is not important, but, as we will explain, the spatial homogeneity is very important. Measurements with Nb cylinders, processed like the cavities, showed that the variation of flux penetration depth λ(Hdc) with a dc magnetic field Hdc parallel to the cylinder surface changed markedly with surface treatment. This variation of λ(Hdc) shows several features, which are related to surface properties, namely, the reversibility near Hc1 and the signal at Hc2 as indications for roughness or oxygen in the surface sheath, the irreversibility between Hc1 and Hc2 as an indication for inhomogeneities, especially NbO precipitates, in a Nb surface layer. For example, by this method we observed that the usual cool down from 400 to 50°C in the UHV furnace deteriorates a Nb surface layer of several μ thickness. These surface properties obtained with λ(Hdc) are not only important for achieving better rf cavities but also for ac power transmission lines.

The surface preparation technique was used to estimate the sensory cell population and density in the organ of Corti of seven harp seals and four ringed seals. The average total of inner hair cells for the harp seal was 3654 (3078–263) as compared with an average total of 3232 (3120–3354) in the ringed seal. The average total number of outer hair cells in the harp seal was 14 318 (12 173 – 15 709) as compared with an average total of 13 497 (12 903 – 14 894).The distribution of outer and inner hair cells showed an increase in density from base to apex. An increase in density of about 21% and 29% was observed in the inner hair cells of the ringed and harp seal. The increase in density for each row of outer hair cells was 21% in the harp seal and 17% in the ringed seal. The density of outer hair cells per unit surface area decreased from a maximum value at the base to about half its value at the apex.The average total sensory cells of seals exceeded the average total sensory cells of both man and dolphin but were within the range of variation of the human.

With the growing concerns over change in Federal regulations, and the increase in waste disposal costs, the oil and gas maintenance industry is in need of an alternative solution to fit these specifications. They are in need of an innovative tactic that is controlled, safe, predictable, and most importantly, able to provide an ultra-clean surface that meets the set industry performance standards. Little do most people know, this solution we are all looking for was created in the early 1800s, and used by coal miners as a method to remove loose debris and coal. This solution is the use of water pressure to remove contaminants and various materials. The method has evolved since the early 1800s to now use ultra-high-pressure water to effectively remove coatings and contaminants from surfaces. The process is now known as UHP Waterjetting. In 1994, the US Navy embraced this method as a means to reduce waste streams, and provide a solution to ships breaking up at sea because of corrosion. Surface preparation techniques have evolved with the acceptance of UHP waterjetting (UHP WJ). The new technique has proven to provide benefits in not only workflow, but also in the overall project's pocketbook as well. With quality requirements rising and budgets for maintenance activities decreasing, UHP WJ has become the ideal surface preparation solution. With abrasive users still hesitant to make the change to water, this paper aims to provide you with a wealth of knowledge surrounding the topic and more details on one popular method of utilizing this solution, remote controlled robotics.

Joints are introduced into concrete pavement to control cracking and to allow thermal movements. Sealing of concrete pavement joints to keep incompressibles and water out of the system is critical for the long-term performance of a roadway. Water introduced into the system through the joints can destabilize the slabs and accelerate the degradation of the load transfer rods. Incompressibles introduced into the joints will retard and inhibit the designed movement of the joints. This study assesses the durability of three different sealants placed in assemblies utilizing concrete typical of roadways with various surface preparation methods. Sawed concrete blocks were evaluated with various consolidating primers on concrete. Joint assemblies were fabricated with sealant according to ASTM C719-14 dimensions and subjected to tension movement after immersion in MgCl2 solutions at various temperatures. Visual inspection based on ISO 19862 criteria for adhesion performance was recorded so that surface preparations/treatments could be compared to one another. Controls of joint assemblies immersed in tap water at elevated temperatures showed that MgCl2 had a significant impact on the durability of two of the three sealants tested. This test method of evaluating the adhesion degradation in salt solutions at elevated temperatures proved to be a highly effective method of inducing failures in two of the three sealant materials tested.

The adhesion of a plasma polymer and the corrosion protection offered to aluminum alloy substrates depends on the cleanliness of the substrate surface and the state of oxides on the aluminum alloy surface. Both factors are dependent on what type of alloy is used, and consequently, the best preparation of the substrate surface differs on the type of aluminum alloy. Oxygen plasma treatment is effective for the elimination of organic surface contamination, but plasma treatment, such as that of mixed argon and hydrogen, cannot be used to modify the surface state of oxides on these alloys. This is because oxides of aluminum are stable and thus resist plasma modification, and prolonged plasma treatment has been observed to change concentrations of alloy components at the surface due to the heating of the alloy. Chemical cleaning of the surface is necessary before the application of the plasma polymer used for corrosion protection enhancement. Once the surface was properly prepared, a plasma polymer of trimethylsilane (TMS), prepared by cathodic polymerization, adhered well to aluminum alloys investigated in this study. Major adhesive failure, however, occurred as a consequence of reactor contamination when hexafluoroethane (HFE) plasma treatment of initially formed TMS plasma polymers was employed. Plasma pretreatment of the substrate with O2 or postplasma treatment of the plasma polymer of TMS with Ar (instead of HFE) was effective in eliminating the surface‐contamination effect on the adhesion. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1387–1398, 2002