Type Of Surface Treatment Research Articles

Influence of surface treatment on the surface energy of an aluminium substrate

The mechanisms by which adhesion occurs are known. In all cases, the search for an adequate surface condition is decisive in achieving a good adhesion. For this reason, the researches usually work on modifying the surface roughness or improving the thermodynamic characteristics of the surface. The objective on this work is to analyse influence of different attack types (chemical, mechanic, with laser …) which are used to improve surface finish, roughness and surface energy. We have analysed the effects that have produced in the contact angle, measuring the surface energy by the Zisman method. The results revealed that the method of attack has more influence on the value of surface energy than the values of roughness obtained, which can make rethink the type of surface treatment to improve adhesion.

Application of zirconia surface coating to improve fracture resistance and stress distribution of zirconia ceramic restorations

Zirconia ceramic restoration (ZCR) has a higher fracture incidence rate than metal ceramic restoration. Different surface treatments were used to improve fracture performance of ZCR such as grit blasting (GB) by aluminium oxide powder. This type of surface treatment generate residual stresses on veneering ceramic causing crack initiation and ending with a fracture. In order to overcome the stress generated by GB, zirconia surface coating is used as a surface treatment to improve fracture resistance and to accommodate stresses along the ZCR layers. Fifty zirconia ceramic crowns were fabricated and divided according to the type of surface treatment into three groups; the first group is (ZG), involving 20 cores were coated with a mixture of partially-sintered zirconia powder (PZP) and glaze ceramic powder; the second group is (ZL), including of 20 cores were coated with PZP and liner ceramic paste. The third group is grit blasting (GB), preparing of 10 fully sintered cores at 1350 °C which then abraded by 50 µm aluminium oxide powder. The groups ZG and ZL were further subdivided into ZG26, ZG47, ZL26 and ZL47 based on two PZP sizes (47 and 26 µm). Each treated core was veneered with the veneering ceramic layer. Fracture resistance (FR) was measured by the universal testing machine. Finite element analysis (FEA) was used to simulate the stress distributions on the coated and non-coated zirconia crown models. The ZG47 group had higher FR (647.92 ± 97.33 N) and a significant difference (P < 0.00) compared to GB and other coated groups. The FEA exhibited lower and evenly distributed stresses of the zirconia glaze model than the zirconia liner and the non-coated models. The ZG47 coating considered as an alternative method to GB treatment which increases the FR which significantly improved the clinical performance of the ZCR.

Experimental investigation of mortar mechanical properties for glass brick masonry

The main advantage of solid bricks over hollow blocks is substantially higher compressive strength. On the other hand, solid bricks have much higher thermal conductivity, which would lead to major heat loss when used for exterior walls. Masonry pillars and walls are usually loaded in compression and/or bending resulting from the eccentricity of vertical load or wind load. In case of solid glass bricks, compressive strength is about ten times higher than tension strength therefore the limiting factor of the glass masonry is tensile stress resulting from the bending. Whether compared to ceramic or concrete bricks masonry, the glass bricks have a smooth and non-absorbent surface and the adhesion of the mortar to the glass surface is the critical parameter. Presented paper is focused on the experimental investigation of mortar applicable for glass brick masonry with regard to use for load bearing brick walls or columns. Shear, compression and tension tests have been recently performed. Shear and tension resistance and failure modes of brick bed joint were determined during series of tests using various mortar composition, two types of surface treatment and different thickness of the mortar joint. Significant influence of the joint thickness on the resistance was found. The compression tests were performed on two small pillars to determine the compression resistance and failure mode of glass bricks walls and pillars. In parallel to these tests, several small-scale tests have been performed to determine flexural and compressive strength of hardened mortar.

Effect of Sandblasting and Zirconia Primer Application on The Zirconia-Cement Shear Bond Strength (An in-vitro Study)

Aim: This study was carried out to evaluate the effect of two types of surface treatments; Sandblasting (Al2O3 110 m) and Zirconia primer (Z-Prime Plus) applicaition on zirconia-resin cement shear bond strength. Materials and Methods: 28 zirconia discs were specially constructed for this study by CAD-CAM machine of dimensions 10 mm diameter and 5 mm thickness. The discs were divided into two groups according to sandblasting surface treatment as the following: Group (I):14 zirconia discs without sandblasting and Group (II):14 zirconia discs after being subjected to sandblasting. These groups are subdivided into two subgroups each according to Z-Primer Plus application. Subgroup A: 7 zirconia discs without primer application and Subgroup B: 7 zirconia discs with primer application. Sandblasting was carried out to fourteen zirconia discs using 110 μm(Al2O3). Zirconia Primer (Z Primer Plus) was applied to 14 zirconia discs.28 composite discs were fabricated according to manufacturer’s instructions with dimensions 5mm diameter and 2.5mm thickness. Cyclic loading was done by 10,000 Cycle, frequency 1.6 Hz, Torque; 2.4 Nm and Weight 3 kg (30 N) and also thermocycling was done, at5oC and 55oC and number of cycles is 500 cycles. Testing shear bond strength was done for all samples using universal testing machine.Results: It was found that the highest shear bond strength mean value recorded for group (IIB) followed by group (IB) then group (IIA) while the lowest mean value recorded for group (IA) The difference between different surface treatment groups was statistically significant as revealed with one way ANOVA test (p 0.05) differences between {(IIB) and (IB)}, {(IB)and (IIA)} and {(IIA) and (IA) }.It was noted that during thermo-mechanical aging a total loss of two samples in group (IIA) and only one sample in group (IA) and their results recorded as zero so not indicated in mean value calculation. Conclusions: The bonding to zirconia is affected by mechanical and chemical surface treatments which are sandblasting and primer application.

Bond strength of resin cement to zirconia treated in pre-sintered stage.

Aim of this study was to evaluate the tensile bond strength (TBS) between resin cement and zirconia surface treated in different sintering stages. Eighty zirconia discs having final dimensions of 12 mm diameter and 3.2 mm thickness were milled then divided into three main groups according to the type of surface treatment performed (group 1: air abrasion using 50 µm Al2O3 particles, group 2: silica coating using Rocatec soft, and group 3: a control group receiving no surface treatment). Groups 1 and 2 were divided into two subgroups each according to the stage in which the surface treatment was performed (subgroup A; surface treatment performed in the pre-sintered stage and subgroup B; surface treatment performed in the post-sintered stage). Discs were later bonded to composite core materials using resin cement then tested for TBS either being subjected to 3 days of water storage or 150 days of water storage and 37,500 thermal cycles. Long-term aging caused a significant decrease in TBS of all subgroups except the subgroup air-abraded in the post-sintered stage. After long-term aging, the group silica coated in the pre-sintered stage showed the significantly lowest TBS compared to all other groups. There was also no significant difference between the subgroups air-abraded and silica coated in the pre-sintered stage. All specimens in the control group debonded during long-term aging. Air-abrading zirconia with Al2O3 at a reduced pressure in the pre-sintered stage may result in durable bond strength to resin cement.

Evaluation of the Effect of Different Types of Abrasive Surface Treatment before and after Zirconia Sintering on Its Structural Composition and Bond Strength with Resin Cement.

This study evaluated the effect of air abrasion before and after sintering with different particle type, shape, and size on the surface morphology, monoclinic phase transformation, and bond strength between resin cement and zirconia surface using primer containing silane and MDP. Airborne particle abrasion (APA) was performed on zirconia before and after sintering with different particle shape and size (50 μm Al2O3 and 25 μm silica powder). 120 square shaped presintered zirconia samples (Amann Girrbach) were prepared (3 mm height × 10 mm width × 10 mm length) and polished with grit papers #800, 1000, 1200, 1500, and 2000. Samples were divided into 6 groups according to surface treatment—group A: (control) no surface treatment; group B: APA 50 μm Al2O3 before sintering (BS); group C: APA 50 μm Al2O3 after sintering (AS); group D: APA25 μm silica powder (BS); group E: APA25 μm silica powder (AS) at a pressure of 3.5 bar; and group F: APA 25 μm silica powder (AS) at a pressure of 4 bar. Samples were analyzed using XRD, AFM, and SEM. The samples were submitted to shear bond strength (SBS) test. A dual cure resin cement (RelyX Ultimate) and primer (Scotchbond Universal) were used. Data were analyzed with ANOVA and Tukey test (α ≥ 0.05). APA in group B significantly increased the surface roughness when compared to all other groups. A significant monoclinic phase transformation (t-m) value was observed in groups C and F and a reverse transformation occurred in presintered groups. The SBS value of group A was 11.58 ± 1.43 and the highest significant shear bond strength value was for groups B (15.86 ± 1.92) and C (17.59 ± 2.21 MPa) with no significant difference between them. Conclusions. The use of APA 50 μm Al2O3 before sintering and the application of primer containing MDP seem to be valuable methods for durable bonding with zirconia. The use of APA 50 μm Al2O3 after sintering induced the highest (t-m) phase transformation.

Macro-polyolefin fiber pull-out behaviour from HPC matrix: evaluation of type of surface treatment

In this paper, the effect of different surface treatment of a smooth Polyolefin macro-fibre (macro-PO) on the pull-out behaviour from high performance cementitious (HPC) matrix is investigated. The macro-PO fibres were treated in the way that grooves provided in longitudinal and transverse directions on the surface. A latex surface treatment also used for macro-PO to evaluate frictional interaction between the fibre and matrix. The details of pull-out test results were compared with un-treated macro-PO to determine the effectiveness of different surface treatment on load-bearing capacity during pulling-out process. From the results of pull-out test it was found that treatment of fibres with mechanical modification in fibre axis direction can increase the bonding strength and the energy absorption capacity during pull-out.

Effects of different surface treatments on the cyclic fatigue strength of one-piece CAD/CAM zirconia implants.

The effects of different surface treatments on cyclic fatigue strengths of computer-aided design and computer-aided manufacturing (CAD/CAM) zirconia implants and its mechanisms were evaluated. One-piece cylindrical screw-type zirconia (Y-TZP) implants with diameters of 4.1-mm were fabricated using CAD/CAM technique; they were divided into four groups according to the type of surface treatment: (i) sintering (control group, CTRL), (ii) sandblasting (SB), (iii) sandblasting and etching with an experimental hot etching solution (SB-ST), and (iv) sandblasting and etching with hydrofluoric acid (SB-HF). The surface morphology and roughness of the implants were evaluated. Tetragonal to monoclinic transformation was measured on the surface by micro Raman spectroscopy. Static and fatigue tests were carried out at room temperature following the ISO 14801:2014 Standard. The cyclic fatigue strength of each group was determined using the staircase method. Specimens that survived the fatigue test were statically loaded to measure the residual fracture strength. Among the four groups, SB-HF exhibited the highest surface roughness. Compared with the CTRL group, the surface monoclinic content was higher after all three types of surface treatments, amongst which, SB-HF had the highest content (39.14%), significantly more than the other three groups (P < 0.01). The cyclic fatigue strengths of CTRL, SB, SB-ST, and SB-HF implants were 530 N, 662.5 N, 705 N, and 555 N, respectively. The fracture strength after fatigue loading was higher than that before fatigue loading with no significant difference (P＞0.05). SB and SB-ST remarkably enhanced the fatigue resistance of zirconia implants, while SB-HF did not. One-piece 4.1-mm diameter CAD/CAM zirconia implants have sufficient durability for application in dental implants.

Effect of different resin cements and surface treatments on the shear bond strength of ceramic-glass polymer materials

Statement of problemThe effect of different surface treatment techniques on the bond strength of different types of ceramic-glass polymer computer-assisted design and computer-assisted manufacturing (CAD-CAM) materials and resin cements after aging is unknown. PurposeThe purpose of this in vitro study was to evaluate the surface roughness of different ceramic-glass polymer CAD-CAM materials after 2 different surface treatments and the effect of material, surface treatment, resin cement, and aging on bond strength. Additionally, it was to determine any correlation between the surface roughness and bond strength. Material and methodsCAD-CAM ceramic-glass polymer materials, a polymer-infiltrated ceramic network (PICN) (VITA ENAMIC), a resin nanoceramic (Lava Ultimate), and a nanoparticle-filled resin (Cerasmart) (1.5 mm in thickness; n=144) were divided into 2 subgroups in terms of surface treatments: airborne-particle abraded or silica-coated. The surface roughness values of specimens were measured. Composite resin cylinders were prepared and bonded to the restorative specimens using 2 different types of resin cements (dual-polymerizing [DP] and light-polymerizing [LP]). Half of the specimens were stored in distilled water for 24 hours, while the other half were submitted to 5000 thermocycles. The shear bond strength was measured, and the failure modes of the specimens were evaluated. The data were analyzed with ANOVA and Tukey HSD tests (α=.05). The correlation between roughness and bond strength values was analyzed using Pearson correlation analysis. ResultsMaterial (P=.012) and surface treatment type (P=.031) significantly affected the surface roughness. For bond strength, significant interactions were found among the material type, surface treatment, resin cement, and aging factors (P=.009). No significant correlation was found between roughness and bond strength (P=.943). ConclusionsThe surface treatment and resin cement type affected the bond strength and surface roughness of tested restorative materials. DP resin cement provided higher bond strength for airborne-particle abraded nanohybrid composite resin materials. LP resin cement achieved a higher bond strength when used with silica-coated, nanoparticle-filled resin and PICN materials.

Evaluation of ionic liquid treated sisal (agave sisalana) fiber as sorbent in biodiesel spill

The global economic development continually demands the use of energy resources, among which various types of oils are widely used. Despite their undeniable economic importance, environmental accidents with these occur frequently. Thus, the search for efficient and low-cost mitigating measures is recurrent. In this context, techniques that use natural adsorbents, such as vegetable fibers, have been studied, since they combine efficiency, selectivity, low cost and sustainability. Studies have been carried out using various types of fibers, natural or chemically treated. The interest in treating the fiber lies in the fact that, changing the chemical structure of the fiber, its oil sorption capacity is increased. Due to the offered advantages, an alternative and promising type of surface treatment using ionic liquids was performed, to the detriment of traditional treatments. Thus, the technical feasibility of the use of sisal fiber treated with ionic liquid for adsorption of biodiesel was studied.

Influence of Surface Treatment on Composite Adhesion in Noncarious Cervical Lesions: Systematic Review and Meta-analysis.

The purpose of this study was to analyze the influence of dentin surface treatments on the retention rate of resin composite restorations in non-carious cervical lesions (NCCLs). Seven randomized clinical trials were included in this review. Data regarding retention rate, type of surface treatment, and the main characteristics of studies were analyzed. Two reviewers performed a literature search up to December 2016 in eight databases: PubMed (Medline), Lilacs, Ibecs, Web of Science, BBO, Scopus, Scielo and The Cochrane Library. Only clinical trials evaluating dentin surface treatments in resin composite restoration in NCCLs were included. Noncontrolled clinical trials, reviews, editorial letters, case reports, case series and studies published in a language other than English, Portuguese, or Spanish were not included. The included studies evaluated different surface treatments, such as using an adhesive system with a frictional technique, drying the dentin, and removing sclerotic dentin by using a bur and applying EDTA before primer use. The analysis considering the mechanical removal of dentin surface with a bur and the application of an adhesive system in a frictional mode showed these treatments improved retention rates of the resin composite restorations in NCCLs ( p<0.05). There is evidence in the literature suggesting that the mechanical removal of dentin surface with a bur and the application of an adhesive system in a frictional mode could improve the retention rates of resin composite restorations in NCCLs. However, the studies showed high heterogeneity, and additional clinical trials are needed to determine the best dentin treatment option in NCCLs.

Effect of surface treatments and coffee thermocycling on the color and translucency of CAD-CAM monolithic glass-ceramic

Statement of problemThe effects of surface treatments and coffee thermocycling on the color and relative translucency of a recently introduced computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic glass-ceramic are unknown. PurposeThe purpose of this in vitro study was to evaluate the effect of coffee thermocycling on the color and relative translucency parameter (RTP) of CAD-CAM monolithic glass-ceramics after different surface treatments. Material and methodsSpecimens (1.5-mm-thick) were sectioned from zirconia-reinforced lithium silicate glass-ceramic (ZLS) (n=18) and lithium disilicate glass-ceramic (LDS) blocks (n=18). Two different types of surface treatments (glazing or polishing) were applied to the specimens. The specimens were subjected to 5000 thermocycles in a coffee solution. The color coordinates of specimens were measured before and after coffee thermocycling by using a spectroradiometer, and color differences and relative translucency values were calculated by using CIEDE2000 color difference and RTP formulas. ANOVA was used to analyze the color difference and relative translucency values by using maximum likelihood estimation and the Satterthwaite degrees of freedom methods. Any significant interaction between surface subgroups was further analyzed by using the Tukey-Kramer adjustment (α=.05). ResultsMaterial type had a significant effect on color difference (P=.018). All color difference values of all materials were smaller than the clinical acceptability threshold (<1.8 units). For relative translucency, material (P<.001) and coffee thermocycling had a significant effect (P=.014), and an interaction was found between the surface treatments and materials (P<.001). The Tukey-Kramer test revealed significant differences between glazed and polished subgroups of LDS material, except for ZLS-glazed and ZLS-polished subgroups. ConclusionsDifferent surface treatments of CAD-CAM monolithic zirconia-reinforced lithium silicate and lithium disilicate glass-ceramics resulted in clinically acceptable color changes after coffee thermocycling. The color changes in all groups, except for LDS-polished, were not perceivable. Lithium disilicate was more translucent than zirconia-reinforced lithium silicate before and after coffee thermocycling. Coffee thermocycling decreased the translucency of both of the materials. Different surface treatments affected the translucency of only lithium disilicate for tested thickness.

Effect of different surface treatments on shear bond strength of zirconia bonded to dentin with two resin luting cements

All-ceramic materials, especially silica-based lithium di-silicate and non-silicatebasedZirconia have become a topic of interest in the field of dentistry. It is stilldifficult to achieve a strong and durable resin-ceramic adhesion, especially resin-Zirconia bonding, focusing on the latest resin bonding techniques including surfacetreatment, priming and cementation.The purposes of this study was to evaluate the effect of different surfacetreatments on shear bond strength of zirconia bonded to dentin with two resin lutingcements.A total 60 zirconia discs 3mm thickness and 6 mm diameter subjected tothree types of surface treatments,irradiated with CO2 laser,etched with hydrofluoricacid, sandblasted+ceramic primer application,then bonded to dentin with two types ofresin cement (variolinkII and Dentocem). Shear bond strength was measured and thetype of failures were determined. The data were statistically analyzed by one-wayanalysis of variance and Independent T-test. The results of this study showed that thegroups which were sandblasted treated with ceramic primer produced highest shearbond strength followed by hydrofluoric etched groups and CO2 laser irradiated groupsshowed the lowest bond strength. Dentocem resin cement showed better bonding thanvariolink II.The failures were either adhesive (between discs and cement)orcohesive(cements on both disc and dentin).As a conclusion the bonding of Zirconiacan be improved by the different surface treatments especially by sandblastingceramic primer . Dentocem resin cement showed higher shear bond strength thanvariolinkII so promoted better adhesion between dentin and zirconia..

Immediate Repair Bond Strength of Fiber-reinforced Composite after Saliva or Water Contamination.

This in vitro study aimed to evaluate the shear bond strength (SBS) of particulate filler composite (PFC) to saliva- or water-contaminated fiber-reinforced composite (FRC). One type of FRC substrate with semi-interpenetrating polymer matrix (semi-IPN) (everStick C&B) was used in this investigation. A microhybrid PFC (Filtek Z250) substrate served as control. Freshly cured PFC and FRC substrates were first subjected to different contamination and surface cleaning treatments, then the microhybrid PFC restorative material (Filtek Z250) was built up on the substrates in 2-mm increments and light cured. Uncontaminated and saliva- or water-contaminated substrate surfaces were either left untreated or were cleaned via phosphoric acid etching or water spray accompanied with or without adhesive composite application prior applying the adherent PFC material. SBS was evaluated after thermocycling the specimens (6000 cycles, 5°C and 55°C). Three-way ANOVA showed that both the surface contamination and the surface treatment signficantly affected the bond strength (p < 0.05). Saliva contamination reduced the SBS more than did the water contamination. SBS loss after saliva contamination was 73.7% and 31.3% for PFC and FRC, respectively. After water contamination, SBS loss was 17.2% and 13.3% for PFC and FRC, respectively. The type of surface treatment was significant for PFC (p < 0.05), but not for FRC (p = 0.572). Upon contamination of freshly cured PFC or semi-IPN FRC, surfaces should be re-prepared via phosphoric acid etching, water cleaning, drying, and application of adhesive composite in order to recover optimal bond strength.

Changing in Fatigue Life of 300 M Bainitic Steel After Laser Carburizing and Plasma Nitriding

In this work 300M steel samples is used. This high-strength steel is used in aeronautic and aerospace industry and other structural applications. Initially the 300 M steel sample was submitted to a heat treatment to obtain a bainític structure. It was heated at 850 °C for 30 minutes and after that, cooled at 300 °C for 60 minutes. Afterwards two types of surface treatments have been employed: (a) using low-power laser CO2 (125 W) for introducing carbon into the surface and (b) plasma nitriding at a temperature of 500° C for 3 hours. After surface treatment, the metallographic preparation was carried out and the observations with optical and electronic microscopy have been made. The analysis of the coating showed an increase in the hardness of layer formed on the surface, mainly, among the nitriding layers. The mechanical properties were analyzed using tensile and fatigue tests. The results showed that the mechanical properties in tensile tests were strongly affected by the bainitic microstructure. The steel that received the nitriding surface by plasma treatment showed better fatigue behavior. The results are very promising because the layer formed on steel surface, in addition to improving the fatigue life, still improves protection against corrosion and wear.

Bond strength of self-adhesive resin cement to base metal alloys having different surface treatments

This study aimed to assess and compare the shear bond strength of self-etch and self-adhesive resin cement to nickel-chromium-cobalt alloy with different surface treatments. In this in vitro study, a total of 120 disks were fabricated of VeraBond II base metal alloy. Specimens were divided into 15 groups of 8 based on the type of cement and surface treatment. The five surface treatments studied included sandblasting alone, application of Alloy Primer with and without sandblasting, and application of Metal Primer II with and without sandblasting. The three cement tested included Panavia F2.0, RelyX Unicem (RU), and G-Cem (GC). After receiving the respective surface treatments, the specimens were thermocycled for 1500 cycles and underwent shear bond strength testing. Data were analyzed using SPSS 20.0 and three-way analysis of variance. P values of the significant level of 0.05 were reported. The results exhibited that the mean bond strengths in sandblasted groups were higher than nonsandblasted one. These differences were significantly higher in the sandblasted groups of Panavia F2.0 and RU cement (P < 0.05). The mean bond strength values between GC and Panavia F2.0 were not statistically significant (P > 0.05). The highest bond strength was recorded for Panavia F2.0 with the surface treatment of both sandblasting and Metal Primer II. Based on the results, sandblasting improves the shear bond strength of self-etch and self-adhesive resin cement to base metal alloys. The best results can be achieved with a combination of sandblasting and metal primers. The performance of resin cement depends on to their chemical composition, not to the type of system.

Comparative Study between Resin Nano Ceramic and CAD/CAM Ceramic Regarding Their Fracture Resistance, Microtensile Bond Strength and Fatigue Resistance

Purpose: In an attempt to improve the mechanical properties, industriallyCAD/CAM ceramics blocks have been introduced to dentistry. This study was directed to investigate the influence of the material thickness on the fracture resistance ofCAD/CAM Resin Ceramic and CAD/CAM Ceramic and asses the fatigue resistance of class II mesio-occlusal-distal (MOD) inlays of both materials and compare their micro-tensile bond strength (μTBS) after cementation by two different adhesive resin cements. Materials and Methods: A total of 70 specimens were fabricated. The specimens were divided according to the material used into two main groups (n= 35). Group 1 specimens were fabricated from CAD/CAM Resin Ceramic (Vita Enamic), whereas Group 2 specimens were fabricated from Lithium disilicate glass ceramic (IPS e-max CAD). Specimens of each group were further subdivided into 3 subgroups according to type of testing (microtensile bond strength test, fracture resistance and fatigue resistance tests). Specimens of subgroup of microtensile bond strength test (n=40) were further subdivided into 2 divisions (n=20) according to type of surface treatment (control and sandblasting). Then each division was further subdivided into 2 subdivisions (n=10) according to type of cement used (Rely X Ultimate and multilink N). Furthermore, subgroup of fracture resistance test (n=20) was further divided into 2 division (n=10) according to thickness (0.5 mm and 3 mm). Two-way analysis of variance ANOVA test and three-way analysis of variance ANOVA test of significance were done for comparing variables. Results: For microtensile bond strength, it was found that the highest μ-tensile bond strength value was recorded for Multilink N control subgroup (54.07±7.9 MPa), while the lowest μ-tensile bond strength mean values was for Rely X Ultimate sandblasted subgroup (37.12±2.5 MPa) and IPS e-max CAD. Results revealed that the highest μ-tensile bond strength mean value was recorded for Rely X Ultimate

Polyelectrolyte Brush-Grafted Polydopamine-Based Catalysts with Enhanced Catalytic Activity and Stability.

Three types of surface treatments, namely, polyethyleneimine (PEI) coating, short PEI (S-PEI) grafting, and long PEI (L-PEI) grafting, were performed on polydopamine (Pdop)-based catalysts to enhance their catalytic activity and stability. Brush-grafted catalysts were prepared by the stepwise synthesis of Au and short (or long) PEI brushes on Pdop particles (PdopP/Au/S- or L-PEI grafting). PEI-coated Pdop-based catalysts (PdopP/Au/PEI coating) were also prepared as non-brush-grafted catalysts. Among the surface-treated PdopP/Au catalysts, the brush-grafted catalysts (S-PEI and L-PEI grafting) exhibited excellent and stable catalytic performance because the brush grafting enabled the protection of the catalysts against harsh conditions, effective transfer of reactants to the catalysts, and confinement of reactants around the catalysts. The brush-grafted catalysts could also more effectively decompose larger dyes than the non-brush-grafted catalysts. The process-to-effectiveness of PEI coating is the best because the release of Pdop from PdopP/Au was moderately inhibited by the presence of only one layer of PEI coating on the PdopP/Au. Thus, this approach could be an alternative method to enhance the stability of PdopP/Au catalysts.

The Effect of Denture Base Repair with Special Type of Acrylic O-Cry1 and Different Surface Treatments on Impact Bond Strength of Acrylic Resin (Comparative Study)

Background: the common problem in prosthodontics is a fracture of the denture base and it represents an annoyance for the dentists. Therefore, the option of increasing repair strength using new reinforcement materials is of great interest to prosthodon- tists. The purpose of this study was to assess the effects of using a special type of acrylic o-cry1 in repair instead of heat cure acrylic resins and different surface treatments on impact bond strength using Ivomet and conventional curing methods. Materials and Methods: One hundred thirty specimens of heat acrylic resins were constructed. There are 2 main groups accord- ing to curing methods (Ivomet and conventional method curing). For each group, there were 6 groups according to the surface treatments used (untreated, monomer, thiner, zirconium oxide, glass fiber and butt joint with monomer) as well as control group. Results: The study showed that the control group had a higher value of impact strength than other groups which were cured by conventional method. For Ivomet curing, the butt joint with monomer and glass fiber groups improved the impact bond strength in comparison to other groups. Conclusion: the butt joint with monomer treatment and glass fiber groups have improved the impact strength of the repaired acrylic resins when using Ivomet compared with other groups. On the other hand, the use of thiner and zirconium oxide reduced the impact bond strength when using the conventional curing method. The use of Ivomet device in curing samples improved the impact strength of acrylic repaired with O-cry1.

The effect of grain size on the surface properties of titanium grade 2 after different treatments

This paper presents findings concerning the influence of the grain size of titanium on its surface properties and on the efficiency of surface treatments. The investigations were performed on titanium grade 2 of two grain sizes. The chemical composition and chemical state of the surface were analyzed by X-ray photoelectron spectroscopy. Different types of surface treatment were applied: plasma nitriding, and a combination of chemical and mechanical modifications using etching with hydrofluoric acid and shot peening. The effect of the grain size on surface treatments was evaluated through roughness quantification, hardness measurements, and observations of the surface and microstructure.The investigations showed that grain size influences the wettability and surface free energy of titanium grade 2. A reduction in grain size is beneficial for the effectiveness of plasma nitriding. The results also indicate that the grain size of titanium grade 2 affects the surface morphology after shot peening and chemical etching with HF acid; these various methods make it possible to modify the surface roughness of titanium over a wide range. The present paper demonstrates that grain size affects the surface properties of titanium grade 2 and can be used as an additional parameter in optimizing the microstructure and properties of surface layers and coatings.