Abrasive System Research Articles

Development of Ce/Cu co-doped dendritic mesoporous silica nanoparticles (DMSNs) as novel abrasive systems toward high-performance chemical mechanical polishing

Development of novel abrasive systems with functional activities and physicochemical properties are of great significance in the reactive oxygen species (ROS)-enhanced chemical mechanical polishing. In this work, Ce single-doped and Ce/Cu co-doped dendritic mesoporous silica nanoparticles (DMSNs), namely Ce−DMSNs and Ce/Cu−DMSNs, were produced via a simple impregnation and thermolysis procedure. The Ce and/or Cu species involved in DMSNs frameworks were characterized through X-ray diffractometry, infrared spectroscopy, scanning electron microscopy, energy dispersive spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption techniques. We report the evolution of surface morphology and roughness, defects, peak-to-valley data, image surface area difference, and material removal efficiency during ROS-enhanced polishing experiments toward silica materials. All the pure, Ce single-doped, and Ce/Cu co-doped DMSNs abrasive systems offered nearly defect-free surfaces with close-to-atom scale roughness. It might be attributed to the “springlike effect” and “soft polishing/abrasion”, possibly originating from the low-modulus DMSNs carriers. Among these abrasives, the Ce/Cu co-doped DMSNs systems achieved an evident improvement in removal efficiency, especially under ultraviolet irradiation-assisted polishing conditions. The coexisted Ce(Ⅲ)/Ce(Ⅳ) and Cu(Ⅰ)/Cu(Ⅱ) couples might be responsible for the effective production of ROS in photocatalysis and Fenton-like processes, thereby contributing to the Si–OH and Ce(Ⅲ)−O–Si bonding formations. The role of the developed Ce/Cu co-doped DMSNs abrasive systems in ROS-enhanced polishing processes was discussed.

Effects of abrasive grain size of flexible body-armor-like abrasive tool (BAAT) on high-shear and low-pressure grinding for zirconia ceramics

Zirconia ceramics exhibit remarkable performance. However, the high hardness and brittleness poses enormous challenges for machining. This study is integrally focused on preparing a flexible body-armor-like abrasive tool (BAAT) with enhanced tangential-to-normal force ratio. The rheological characteristics of the BAAT abrasive system with different abrasive grain were investigated. A series of grinding tests were conducted on a precision grinding machine. The grinding performance of the BAAT with different abrasive grain sizes was examined. Surface roughness (Ra) variation and tangential-to-normal force ratio were analyzed, together with the investigation of the three-dimensional surface morphology and surface hydrophilicity. It was found that smaller abrasive grain sizes ultimately generated lower surface roughness values after grinding. Under the optimal grinding conditions, the surface roughness (Ra) of zirconia ceramics decreased from 102 nm to 1.7 nm after 5 grinding strokes (∼1 min). Meanwhile, uniform grinding textures were obtained.

Trivalent lanthanum and ytterbium doped meso-silica/ceria abrasive systems toward chemical mechanical polishing (CMP) and ultraviolet irradiation-assisted photochemical mechanical polishing (PCMP)

Ceria (CeO2)-based abrasives are widely utilized in ultra-precision grinding and chemical mechanical polishing (CMP) applications over silica materials due to their unique physicochemical properties. Both mechanical and chemical contributions to polishing processes are highly affected by the size, shape, structure, component, defect of CeO2 abrasives. Herein, the composites involved mesoporous silica (mSiO2) cores and La- or Yb-doped CeO2 shells were synthesized and characterized in terms of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, scanning transmission electron microscopy–energy dispersive X-ray mapping methods. The polishing effectiveness of the proposed composites toward quartz glass was experimentally evaluated under both CMP and ultraviolet irradiation-assisted photochemical mechanical polishing (PCMP) conditions. The polishing results indicated that the low-modulus mSiO2 cores strongly exerted the cushion effects for the friction and abrasion to substrates. Consequently, the heterostructured mSiO2/La-CeO2 and mSiO2/Yb-CeO2 abrasive systems offered nearly non-damage and ultra-smooth surfaces with angstrom-level roughness compared to conventional rigid abrasives. The enriched Ce3+ and oxygen vacancy defects at La- and Yb- doped CeO2 surfaces were responsible for the improvements of tribochemical and photochemical activities, thus allowing evidently enhanced removal efficiency with the assistance of ultraviolet irradiation. A possible polishing mechanism on the multi-component abrasive systems was also proposed.

The influence of CeO2 abrasive size on the performance of photocatalytic assisted chemical-mechanical polishing by Y/Pr co-doping strategy

The synergistic effect of photochemical oxidation activity and tribochemical ability of CeO2 material is a necessary prerequisite for the formation of photocatalytic assisted chemical-mechanical polishing (PCMP) abrasive system. However, it is precisely due to the large band gap (∼ 3.2 eV) of CeO2 and the high recombination rate of photogenerated carriers that the improvement of the photocatalytic oxidation activity of traditional CeO2 photocatalysts is greatly limited, thus preventing the further wide application of cerium-based abrasives in PCMP. Based on this, a series of Ce1–2xYxPrxO2 abrasives were synthesized by molten salt method to improve the performance of cerium oxide based polishing paste with PCMP. The physicochemical properties of Ce1–2xYxPrxO2 samples were analyzed by a series of characterization methods. The results show that Ce1–2xYxPrxO2 abrasive has a normal octahedral shape with a particle size of 190 ∼ 260 nm. With the increase of doping amount, the particle size of abrasive decreases gradually, but the photocatalytic activity increases. Compared with undoped CeO2 abrasives, the removal rate (RR = 932.42 nm/min) of quartz glass by Ce1–2xYxPrxO2 abrasive was increased by about 87.10%. At the same time, the surface quality has been significantly improved. A smooth, flawless and low roughness surface was obtained. The improvement in surface quality can be demonstrated by reducing surface roughness (Ra). The Ra of quartz glass decreased to 0.36 nm after Y3+/Pr3+ co-doped CeO2 abrasive by PCMP (the original Ra of glass was 1.08 nm). It was considered that the size of the abrasive had a close relationship with the surface quality and the RR of the polished glass. Meanwhile, characteristic co-doping strategy was conducive to increase the Ce3+ and oxygen vacancy concentration of CeO2 particles, which optimized the separation efficiency of the photogenic carrier of the photocatalyst. This further promoted the generation of oxidizing active substances in the polishing slurry, and therefore expediting the formation and removal of the chemical reaction soft layer. The removal mechanism of Ce1–2xYxPrxO2 abrasives in PCMP process was discussed.

Pavement preventive maintenance decision-making for high antiwear and optimized skid resistance performance

Insufficient pavement skid resistance due to traffic loads and environmental factors is a major cause of vehicular accidents. Hence, continually monitoring the pavement skid resistance has great theoretical significance and is crucial for practical maintenance. A pavement accelerated abrasion system developed by the research team, a high-precision 3D layer scanner, and a pendulum tribometer are used for lab testing. Forty-eight sets of asphalt pavement texture and friction coefficient data for 11 abrasion stages were collected, each comprising 20,000 abrasion cycles. Afterward, a model of asphalt pavement skid resistance deterioration was formulated by analyzing the downward trajectory of the asphalt pavement texture and friction coefficient indexes. The developed deterioration model had a high prediction accuracy with an R2 value of 91.64%, and the corresponding curve met engineering requirements. Subsequently, four pavement maintenance techniques, namely synchronous gravel sealing, microsurfacing, ultrathin overlaying, and thermal generation, were applied to rutted slab specimens after grinding to perform five additional stages of abrasion tests. Through comparisons with the established pavement skid resistance deterioration model, the optimal maintenance timing under the abrasion test conditions of this study was determined as 230,000 abrasion cycles, as determined via the time/pavement condition analysis approach. Cost-effectiveness analysis was performed for different surface treatment techniques, which yielded an equivalent annual cost of 6.7 for the SMA-5 ultra-thin overlay, which was identified as the most promising maintenance approach. This study provides a scientific basis for preventing traffic accidents and improving traffic safety by offering valuable insights into the evolution of pavement skid resistance and offers guidance on decision-making for the preventive maintenance of pavements for high-antiwear and optimized skid-resistance performance.

Development and characterization of a novel RE3+ doped Core-shell CeO2 abrasive system and its glass CMP investigations

In recent years, Ultra-Thin Glass (UTG) has attracted substantial market attention due to its multi-scenario applications. One of the technical cores in UTG manufacturing is the abrasive design of the chemical mechanical polishing (CMP) process. The present work proposed rare-earth-doped core–shell structured PS@CeO2, PS@CeO2:La, and PS@CeO2:Yb abrasives synthesized by a low-temperature two-step method. The core–shell abrasives are large uniform nanospheres with a size of about 375 nm ∼ 450 nm. According to the matching effect of RE3+ radii and defect sizes, La3+ with larger radii exhibits a more substantial modulation effect than Yb3+ upon the lattice distortion and Ce3+/Ce4+ chemical shift. The CMP results revealed the superior polishing efficiency and better flattening ability of core–shell abrasives. The optimized PS@CeO2:La shows the best glass polishing ability (MRR = 480.22 nm/min, Ra = 0.32 nm), which is attributed to the increased Ce3+ composition from 9.79% to 28.14% (compared with the pristine PS@CeO2) and large particle size, indicative of potential applications of novel abrasive systems in the field of glass polishing.

Highly dispersed Gd-CeO2 nanocrystals supported on mesoporous silica composite particles towards photochemical (photo-assisted chemical) mechanical polishing

Nanoparticles (NPs) are widely used in polishing slurries for ensuring desired material removal and global planarization. Herein, novel multicomponent core–shell abrasive systems have been fabricated via an efficient chemical approach towards photochemical (photo-assisted chemical) mechanical polishing (PCMP) processes. The developed composite particles involved low-modulus mesoporous silica (mSiO2) cores and high-activity Gd-doped ceria (CeO2) shells. Compared to commercial CeO2 NPs, the mSiO2@CeGdO2 abrasives enabled superior fused silica surface quality in both CMP and PCMP tests. Furthermore, the as-proposed composites allowed an evident removal efficiency enhancement in the presence of ultraviolet light radiation. The improved polishing performance can be attributed to (i) the optimization of interfacial contact state and material removal behavior, (ii) the increasements of trivalent cerium and oxygen vacancy, and (iii) the enhancement of photochemical and tribochemical activities of the mSiO2@CeGdO2 heterostructured abrasive systems. The purpose of this work is to provide some contributions to the rational design and fabrication of functional abrasive systems for high-performance PCMP and other field-assisted finishing practices through abrasive structure regulation, surface chemistry, and defect engineering.

Effect of Silica-Modified Aluminum Oxide Abrasion on Adhesion to Dentin, Using Total-Etch and Self-Etch Systems

This study compared the shear bond strength (SBS) and micromorphology of composite resin to human dentin after pre-treatment with silica-modified aluminum oxide air abrasion. Forty-six molar teeth were treated with either Scotchbond Multi-Purpose (SCMP) or Clearfil SE Bond (CLSE) adhesive. Buccal surfaces were pre-treated with the CoJet air abrasion system (SB), and lingual surfaces were controls. The adhesion of light-cured resin composite to the treated dentin surface was evaluated with SBS. After debonding, substrate surfaces were examined with an optical microscope for failure analysis. In addition, 15 molar teeth were sectioned and randomly assigned to one of five groups, according to the dentin surface pre-treatment and adhesive type, and examined with high-vacuum scanning electron microscopy/energy dispersive X-rays (SEM/EDS). The type of adhesive had a significant effect on SBS (p = 0.000); CLSE had the highest values. SB did not affect SBS (p = 0.090). SEM/EDS revealed residual aluminum and/or silicon on all dentin surfaces after SB, except for the control. Treatment with 32% phosphoric acid in the SCMP adhesive decreased the amounts of aluminum and silicon compared to SB dentin only, whereas CLSE resulted in similar quantities of aluminum and silicon as air-abraded dentin. The results of this study indicate that CLSE might have a higher bond strength to dentin than SCMP. Pre-treatment with SB does not appear to affect bonding strength.

Double-layered core–shell heterostructures of mSiO2@CdS@CeO2 abrasive systems toward photochemical mechanical polishing (PCMP) applications

Photochemical mechanical polishing (PCMP) technique, involved the cooperation of light-driven surface modification and force-induced material removal, is expected to be a clean, high-quality, and high-efficiency processing method. Herein, mSiO2@CdS@CeO2 hybrids with mesoporous cores and double-layered core–shell heterostructures were constructed through a three-step strategy and utilized as novel abrasive systems towards PCMP applications. Morphological, structural, and optical characterizations were systematically performed to investigate the correlation between components and polishing performances of the proposed abrasive systems. The created CdS–CeO2 heterojunction contributed to the efficient separation of photogenerated charge carriers and the production of highly reactive oxygen species, thus promoting the formation of photochemically reacted layers. The tribochemical activity and material removal enhancements might be attributed to the enrichments of trivalent cerium and oxygen vacancy in CeO2 layer after introducing CdS intermediate layer. Moreover, the involved mesoporous SiO2 cores were responsible for the optimized abrasive–wafer interface contacts and the eliminated surface damages. As expected, the proposed abrasive system enabled the nearly scratch-free and atomically planarized surfaces with angstrom-level finish (∼0.14 nm Ra, ∼0.18 nm Rq, ∼0.21 nm Rz), and simultaneously offered a ca. 63.8% of removal efficiency enhancement in PCMP compared to conventional CMP.

A comparison of human dental pulp stem cell activity cultured on sandblasted titanium discs decontaminated with Er:YAG laser and air-powder abrasion: an in vitro study.

Decontamination of implant surfaces is important to the treatment of peri-implantitis. Er:YAG laser and air-powder abrasion system are regarded as the most effective means of decontamination of implant surfaces. The aim of this in vitro study was to compare the activity of human dental pulp stem cells (hDPSCs) cultured on decontaminated sandblasted titanium discs using Er:YAG laser irradiation and air-powder abrasion. Forty-five titanium discs were contaminated with Escherichia coli (E. coli) bacteria and fifteen titanium discs served as sterile control groups. Thirty contaminated titanium discs were decontaminated with Er:YAG laser or air-powder abrasion system and fifteen contaminated discs were used as contaminated control group. Afterwards, hDPSCs were seeded on all sixty experimental titanium discs. The effects of two decontamination tools on hDPSCs viability were evaluated by MTT assay. Alkaline phosphatase (ALP) activity assay, quantitative real-time PCR analysis and alizarin red staining method were performed to assess hDPSCs osteogenic differentiation. Scanning microscope electron (SEM) was also used to evaluate the effects of two different decontaminated methods on cellular morphology. Our study showed that decontamination using Er:YAG laser caused maximum cell viability. However, the ALP activity was not different in laser and air-abrasion groups. The significant expression of an osteoblastic marker and stronger Alizarin red staining were observed in laser irradiation groups. In addition, SEM observation indicated that grown cells were more stretched and more filopodia in Er:YAG-treated discs. In the present study, Er:YAG laser and air-powder abrasion improved the activity of the cells cultured on the decontaminated titanium discs. However, in comparison with air-powder abrasion, Er:YAG laser was more effective.

Copper-incorporated dendritic mesoporous silica nanospheres and enhanced chemical mechanical polishing (CMP) performance via Cu2+/H2O2 heterogeneous Fenton-like system

The structure-dependent properties of abrasive particles play an extremely important role in atomic and close-to-atomic scale manufacturing. In this work, copper-incorporated dendritic mesoporous silica (D-mSiO2) nanoparticles were fabricated via a simple synthesis strategy of solvothermal post-treatment approach. As revealed by XRD, FTIR, HAADF-STEM and the corresponding EDX elemental mapping, some Cu ions were converted into CuO nanocrystals, and others were incorporated into D-mSiO2 frameworks. High-resolution AFM confirmed that the Cu- modified D-mSiO2 abrasives afforded nearly defect-free and atomically planarized dielectric film surfaces with angstrom-level roughness, and at the same time, enabled a significant improvement in removal efficiency. The involved Cu2+-catalyzed heterogeneous Fenton-like reaction in the presence of H2O2 might be responsible for the productions of highly reactive species in polishing slurries, thus contributing to the hydration layer formation and the material removal enhancement. The developed Cu-modified D-mSiO2 material is an efficient candidate for functional abrasive systems with better surface planarization capacity and superior material removal rate. Furthermore, the Cu2+/H2O2 heterogeneous Fenton-like system can be expected to a promising method to supplement in existing free radical-assisted polishing.

Wear behavior of UHMWPE composites under oxidative effect

Ultra-high molecular weight polyethylene (UHMWPE) is widely used in sliding systems due to its advanced tribological properties. For this reason, wear comes into prominence as a major deformation mechanism in industrial applications. In most of the applications, components are open to contaminants and thereby being exposed to different kinds of chemicals. Oxidation is one of chemical degradations evolving in acidic environments while accelerating the wear process in the components. Although there are some efforts paid on the wear properties of UHMWPE, literature lacks an attention to combined effect of wear and oxidation in UHMWPE. In the present work, neat UHMWPE specimens were fabricated in a compression molding chamber by varying the molding pressures. After deciding on the optimum pressure at 250 bar, different loadings (2wt%, 4wt% and 8wt%) of Si3N4 particle fillers were included in the polymer matrix. This additive was selected due to its superior wear and oxidation resistance. Oxidation tests were carried out in an acidic medium, which is a realistic oxidative environment for industrial products. An abrasive system was used in the wear tests. According to the results, oxidation leads to a heavy degradation in anti-wear properties of neat UHMWPE that yielding a specific wear rate of 4.99×10ˉ³ mm³/Nm. However, wear resistance is enhanced to a specific wear rate of 3.82×10ˉ³ mm³/Nm by adding fillers up to a limit loading rate of 2wt%.

A study on corrosion and corrosion-wear behavior of Fe-based amorphous alloy coating prepared by high velocity oxygen fuel method

In this study, the corrosion-wear behavior of a Fe-based amorphous alloy coating was analyzed using a pin-on-ring corrosion abrasion system. The Fe-based amorphous alloy coating was prepared by the high velocity oxygen fuel (HVOF) method. The purpose of this article is to study the corrosion-wear behavior of this Fe-based amorphous alloy coating in sea water. The dynamic potential polarization curve and friction coefficient measurement were used to explore the influence of different polarization potentials on the corrosion-wear of the Fe-based amorphous alloy coating. The corrosion behavior of the coating was also analyzed using SEM, TEM and XPS. The experimental results show that under low polarization potential, after the iron oxide is dissolved, the chromium element in the Fe-based amorphous alloy coating will form chromium trioxide to produce a passivation protective layer. However, when the polarization potential is increased, the chromium trioxide will begin to dissolve. Subsequently, the molybdate formed by the passivation layer of molybdenum dioxide and molybdenum trioxide will provide more effective corrosion resistance of this Fe-based amorphous alloy coating. In terms of corrosion-wear behavior, owing to high hardness of the Fe-based amorphous alloy, the wear rate under low polarization potential is very small. When the polarization potential increases, a softer passivation layer will be formed on the surface of the coating, which will cause the wear rate to increase. As the polarization potential is +200 mVSCE, the wear mechanism of the coating is mainly a plowing type. While at high polarization potential (+600 mVSCE), it changes to a corrosive wear type.

Subsurface microstructural dynamic recrystallization in multiscale abrasive wear

This paper evaluates various subsurface microstructures of Hadfield steel worn in different abrasion systems. The abrasion systems are defined according to their abrasion conditions related with the following scales: macro (cone crusher); meso (jaw crusher test) and micro (scratch test) in order to relate the industrial and laboratory conditions. The subsurface microstructures were evaluated by Scanning Electron Microscope, Electron Backscatter Diffraction, X-Ray Diffraction, Focused Ion Beam and Transmission Electron Microscope. The observed wear effects to the surface of the cone crusher mantle are characterized by indentations, grooves, intergranular cracks and grain detachment. The subsurface microstructure of the multiscale abrasive wear conditions was composed of a topmost layer with ultrafine grains, a layer with deformation twins and slip bands. In the cone crusher and the jaw crusher, changes in the shape of the subsurface deformed grains after plastic strain were not observed, leaving deformation twinning as the primary strain mechanism. The cone crusher subsurface microstructure showed dynamic recrystallization characterized by ultrafine-grains, small grains with continuous network carbides in the grain boundary, acicular carbides and annealed twin. The analysis of the ultrafine grains formation considers the energy release at the abrasive/material interface and in the subsurface by deformation as responsible for nucleation and growth of ultrafine grains. The scratch test in {111}//ND grain has the subsurface with ultrafine-grains and deformation twins. The nano-hardness results show that the regions with ultrafine-grains have a higher hardness than the regions with deformed grains, where the plasticity was restored and the hardness of the subsuperficial layer had improved. The models of dynamic recrystallization induced by severe plastic deformation are discussed and correlated to the ultrafine-grains formation.

Macroscopic Model of an Abrasive Tool

When designing an abrasive tool, it is necessary to know the most important properties of the abrasive grain-bond system. The greatest interest is the study of the physical and mechanical characteristics of the abrasive tool: hardness, density, bending strength, modulus of elasticity, Poisson's ratio, coefficient of thermal expansion, thermal properties, etc. There are extensive experimental data on mechanical testing of abrasive tools in which a number of empirical formulas have been obtained to determine the physical and mechanical characteristics of an abrasive tool (grain size, hardness, structure, grain and bond grade, etc.). The article is based on core several assumptions and hypotheses that determine the limits of applicability of the results obtained, within which the theory has a complete and complete model of the behavior of the abrasive tool.

Dental Implants Surface in vitro Decontamination Protocols.

Objective The number of patients rehabilitated with dental implants has contributed to increased incidence of peri-implant diseases. Due to complex and difficult treatment, peri-implantitis is a challenge and an efficient clinical protocol is not yet established. Aim of this study was to evaluate the efficacy of two protocols for in vitro decontamination of dental implants surface. Materials and Methods Twenty titanium implants (BioHE-Bioconect) were used. Implants were divided into five groups ( n = 4). NC group (negative control): sterile implants; PC group (positive control): biofilm contaminated implants; S group: biofilm contaminated implants, brushed with sterile saline; SB group: biofilm contaminated implants, brushed with sterile saline and treated with air-powder abrasive system with sodium bicarbonate (1 minute); and antimicrobial photodynamic therapy (aPDT) group: biofilm contaminated implants, brushed with sterile saline and treated with antimicrobial photodynamic therapy (red laser + toluidine blue O). The implants were contaminated in vitro with subgingival biofilm and distributed in groups PC, S, SB, and aPDT. Each group received the respective decontamination treatment, except groups NC and PC. Then, all implants were placed in tubes containing culture medium for later sowing and counting of colony-forming units (CFUs). Statistical Analysis One-way analysis of variance and Tukey tests were performed, at 5% significance level. Results Significantly fewer CFUs were observed in the aPDT group (19.38 × 10 5 ) when compared with groups SB (26.88 × 10 5 ), S (47.75 × 10 5 ), and PC (59.88 × 10 5 ) ( p < 0.01). Both the aPDT and SB groups were statistically different from the NC group ( p < 0.01). Conclusion Proposed protocols, using air-powder abrasive system with sodium bicarbonate and aPDT, showed to be efficacious in the decontamination of dental implants surface in vitro .

Radiographic Evaluation of Surgical Treatment of Peri-implantitis with Bone Graft Procedure: Case Report

The purpose of this case report was to radiographically evaluate the long-term effect of surgical treatment of peri-implantitis defects using bone graf t procedure for more than 3 years af ter operation. 2 cases of patients who had peri-implantitis induced intrabony defect were included in this study. Patients were treated by surgical procedure which consists of mechanical debridement with air abrasive system and titanium curette, chemical decontamination with tetracycline, and regenerative approach using synthetic bone or xenogenic bone. Clinical reduction of probing pocket depth and radiographic evidence of bone gain was observed and maintained in both patients for 3 years after surgery. Within the limitation of this case report, bony defects were managed effectively by surgical treatment with regenerative bone graft procedure.

The impact of surface alteration on epithelial tissue attachment after the mechanical cleaning of titanium or zirconia surface.

Mechanical plaque removal may alter the surface morphology of the gingival penetration part of the implant. We applied an air-powered abrasive system (AP), titanium curette (TC), stainless curette (SC), ultrasound scaler (US), and titanium brush (TB) which are commonly used to remove plaque, to titanium or zirconia and the changes in surface morphology and the epithelial attach against substrata. (a) The morphological changes of titanium and zirconia after mechanical cleaning were assessed by scanning electron microscopy and a roughness analyser. (b) Oral epithelial cells of rats were inoculated on the surface of the materials after mechanical cleaning, and the adherence of epithelial cells was observed. (c) The maxillary first molars were extracted from the rats and replaced by experimental titanium or zirconia implants. The length of the immunoreactive laminin-332 band was observed at the implant-peri-implant epithelium interface. (a) The surface roughness increased in experimental groups except the AP group. (b) Among the experimental groups, the AP group showed the highest number of attached cells. (c) The length of the immunoreactive laminin-332 band was longer in the control group than those in all five experimental groups. Among the experimental groups, the AP group showed the longest band. All mechanical cleaning methods increased the surface roughness of the materials except AP. AP did not cause distinct implant surface alterations. Surface alteration caused by mechanical cleaning may evoke inferior for epithelial attachment and reduce resistance against foreign infiltration.

Nano-Hydroxyapatite Airborne-Particle Abrasion System as an Alternative Surface Treatment Method on Intraorally Contaminated Titanium Discs.

The aim of this study was to test the nano-hydroxyapatite powder decontamination method on intraorally contaminated titanium discs and to compare this method with current decontamination methods in the treatment of peri-implantitis. Contaminated discs were assigned to six treatment groups (n = 10 each): titanium hand curette; ultrasonic scaler with a plastic tip (appropriate for titanium); ultrasonic scaler with a plastic tip (appropriate for titanium) + H2O2; short-term airflow system (nano-hydroxyapatite airborne-particle abrasion for 30 seconds); long-term airflow system (nano-hydroxyapatite airborne-particle abrasion for 120 seconds); Er:YAG laser (120 mJ/pulse at 10 Hz). There were also two control groups (n = 10 each): contaminated disc (negative control) and sterile disc (positive control). Scanning electron microscopy, energy-dispersive x-ray spectroscopy, and dynamic contact angle analysis were used to determine the most effective surface-treatment method. The highest percentage of carbon (C) atoms was observed in the negative control group, and the lowest percentage of C atoms was found in the long-term airflow group, followed by the short-term airflow, laser, ultrasonic + H2O2, ultrasonic, and mechanical groups. When the groups were examined for wettability, the lowest contact angle degree was observed in the long-term airflow, short-term airflow, and laser groups. Nano-hydroxyapatite and laser treatments for detoxifying and improving infected titanium surfaces may show the most suitable results for reosseointegration.

Abrasion Behavior and Anti-Wear Measures of Debris Flow Drainage Channel with Large Gradient

Debris flow gullies have high potential energy and geomorphic characteristics including a steep longitudinal slope and abundant loose material sources. They often experience debris flow with a strong impact force and a large instantaneous flow. Drainage engineering measures are most commonly used for mitigation in these gullies. However, the abrasion of drainage channels with large gradients (DCLG) is complex and strong because of the high-speed flushing of debris. In this study, the abrasion behavior of debris flow in DCLG is analyzed based on the kinematic characteristics and the theory of composite abrasive wear. Energy dissipation and anti-wear measures are suggested, and their effects are summarized with reference to a case study and in situ observation. The results show that there are four main types of wear morphology in drainage channels. The abrasion system of drainage channels shows the characteristics of system dependency, time dependency and multidisciplinary coupling. Energy dissipation and anti-wear measures include prefabricated reinforced concrete boxes as substrate, transverse roughening belts, adding a wear-resistant admixture, etc. The flow velocity of the debris flow is reduced by 5.7–37.1% after passing through the energy dissipation section. The distribution of abrasion and the mud depth show that the variation trend of the flow velocity in the channel is ”acceleration → deceleration → reacceleration“. According to tracking observations during two flood seasons, the energy dissipation and anti-wear measures are the most effective.