High Abrasion Resistance Research Articles

Anti-flammable, anti-fouling, anti-bacterial treatment of cotton fabrics with MOF-based hybrid coatings for highly efficient oil-water separation

A flame-retardant and hydrophobic coating was deposited on the surface of the cotton fabric via a two-step spray deposition technique. Specifically, the coating was composed of flame retardant components (guanidine phosphate) and hydrophobic species (Ti-MOF and bis(3-aminopropyl)-terminated poly(dimethylsiloxane) (PDMS)) and crosslinked with glutaraldehyde. The limiting oxygen index (LOI) of the coated cotton fabrics increased from 18.0 % to 32.0 % (15#) and 26.5 % (15#-Ti-PDMS) relative to that of the original cotton fabric, and the coated cotton fabrics also self-extinguished in the UL-94 flammability test. Compared with that of the original cotton fabric, the PHRR of the coated fabrics was significantly lower, reaching 80 %. The coated cotton fabrics (15# and 15#-Ti-PDMS) had good antibacterial properties against Staphylococcus aureus (S. aureus). In addition, 15#-Ti-PDMS had high hydrophobicity, good washing and abrasion resistance and good water-oil separation performance. Its water contact angle was 146°. The water contact angle remained above 130° after 10 laundering cycles and 50 scratch cycles. Even under strongly acidic and basic conditions, the water-oil separation efficiency of 15#-Ti-PDMS was greater than 99 %, and it was still greater than 90 % after 10 cycles. Therefore, a simple and effective method for preparing flame-retardant, hydrophobic and antibacterial cotton fabrics was developed.

Investigation of effect of recycled polyester ratio and draw frame passages on flame retardancy of chenille fabric properties

PurposeIn this study, both flame retardancy and sustainability properties were combined in the chenille yarn so that functional and sustainable upholstery fabrics can be produced with optimum energy consumption. The chenille yarn samples were produced from recycled polyester (rPET)-blended binder yarns and fully drawn yarn (FDY) polyester pile yarn. While the pile component of the chenille samples was kept constant, the lock yarns were manufactured as 50% r-PET-50% virgin polyester (PES), 100% r-PET and 100% PES. The binder yarns were also produced in two groups. In the first group, a 2-passage draw frame was used, while a 3-passage draw frame was used in the second group. The chenille yarn samples were applied flame-retardant (FR) finishing.Design/methodology/approachThe knitted upholstery fabric samples were produced from chenille yarn samples via flat knitting machines. The knitted fabrics were applied flame retardancy, bursting strength and abrasion resistance tests according to related standards.FindingsThe test results were analysed, and so the effect of r-PET ratio and draw frame passage number on upholstery fabric flame retardancy, bursting strength and abrasion resistance performance properties were revealed. It was concluded that the number of draw frame passages and the recycled fibre content have no important effect on the flame retardancy. On the other hand, it has been observed that the bursting strength decreases as the recycled fibre content increases and bursting distention results are close to each other. It was seen that the draw frame passage number has no significant effect on both bursting strength and distention. It was revealed that both r-PET fibre content and draw frame passage number have significant effect on abrasion resistance. The samples with 2 draw frame passages provide higher abrasion resistance compared to those with 3 draw frame passage. The lowest abrasion resistance was obtained with 100% r-PET fibre content and the highest abrasion resistance was obtained with 50% r-PET-50% PES.Originality/valueThe results will provide enough knowledge for sustainable chenille yarn design. The recycled fibre content and draw frame passage number can be optimised, and so sustainable chenille yarns can be produced with less energy consumption. Future studies will involve producing chenille yarns with different linear densities and varying draw frame combinations, such as 1, 2 and 3 passages.

Evaluation navigation controlled gate of aging spillway on cavitation damage.

High-speed flow of clean water or water with sediment released from aging spillways may cause abrasion and cavitation on the concrete surface gradually. The occurrence of irregularities on the concrete surface can exacerbate the erosion problem. Which might jeopardize the safety of dams constantly, hence the rehabilitation efforts become urgent tasks in dam safety projects. This study employs a 3D Computational Fluid Dynamics (CFD) model to quantitatively analyze the cavitation risk on the aging concrete surface of the Chay 5 spillway in Ha Giang, Vietnam, under various operation scenarios. There are two standards used to measure cavitation: the cavitation index (σ) which indicates the danger due to the drop of pressure in rapid flow, and the new gasification index (β) which takes into consideration the formation and collapse of bubbles behind asperities. Three extreme flood cases may not result in potential cavitation because both σ and β exceed critical thresholds. Regarding the six controlled gate scenarios with normal water level, the σ profiles are approximated 1,0 showing a low likelihood of cavitation damage while the β values are smaller than 0.8, indicating a considerable risk of cavitation. Besides, the opening height of 100 cm poses the greatest risk of creating severe cavitation erosion in the concave area and slope portion. The flip bucket experienced the most vulnerable cavitation when the opening height is 400 cm. In addition, an approach to spillway surface rehabilitation involving specialized mortars has been presented. For aging conveyance structure, gasification index (β) takes into account irregularities surface, providing a more comprehensive assessment of the likelihood of cavitation damage than cavitation index (σ). After rehabilitation with anti-shrinkage high abrasion resistance mortar, the entire spillway surface is smooth. This allows for reducing the cavitation risk and improvement of life service thereof.

The improved viscoelastic properties of long‐length carbon nanotubes reinforced polyamide‐6 composites

AbstractThe semi‐crystallinity, thermoplasticity, high toughness, and light weight of polyamide‐6 (PA6) when reinforced with carbon nanotubes (CNTs) provide outstanding physical properties to the nanocomposites by combining the physical properties of both components. The processing difficulties arising due to the high toughness and abrasion resistance of PA6 and the agglomeration of in‐house synthesized long‐length CNTs can be tackled by melt‐mixing the components inside a twin‐screw extruder with a back‐flow channel. The 0.1–7 parts per hundred ratios (phr) of CNTs reinforced PA6 composites were characterized for their viscoelastic properties through oscillatory rheometry and dynamic mechanical analysis (DMA) at fixed operating conditions. The outcomes showed continuous shiftings in storage and loss modulus values with increasing reinforcements along with a viscoelastic transition at 3 phr CNTs reinforcements observed in DMA. A 19°C rise in glass transition temperature (Tg) was observed in DMA with 0.1 phr CNTs reinforcement, which showed further improvements with increasing CNTs content. The interactions among PA6 and CNTs were further confirmed by X‐ray diffraction (XRD) and Raman spectroscopy curves. These nanocomposites promise mechanical applications in the equipments of automobiles, aerospace, defense, biomedical, bio‐sensors, etc.Highlights Viscoelastic properties study for CNTs/PA6 composites Uniform intermixing of CNTs within PA6 via extrusion with back‐flow channel Detailed analysis of rheometry and DMA of the composites CNTs‐PA6 interactions estimated from rising intensity peaks in Raman spectra and X‐ray diffraction (XRD) Potential candidates for components in automobiles, aircraft, biomedicals, and sports industry

Synergistic enhancement of magic triangle properties of PC tread stocks modified by amine-capped trans-1,4-poly (butadiene-co-isoprene)

The development of high-performance “green tires” with synergistically improved “magic triangle” properties like lower rolling resistance, higher wet-skid resistance and higher abrasion resistance has always been a hot issue. In this work, an effective strategy for developing high-performance “green tires” with simultaneously improved “magic triangle” properties of solution-polymerized styrene-butadiene rubber (SSBR)/cis-1,4-polybutadiene rubber (BR) nanocomposites modified by amine-capped trans-1,4-poly(butadiene-co-isoprene) copolymers (F-TBIR) was proposed. A series of F-TBIR with 10–60 mol% amine-capped efficiency (CE) and 30-90 × 104 weight-average molecular weight (Mw) were synthesized by using heterogeneous TiCl4/MgCl2–Al(i-Bu)3 Ziegler-Natta catalyst with dicyclohexylamine (DCHA) as chain transfer agent (CTA). With the increase in CE of F-TBIR, the silica-filled SSBR/BR/F-TBIR compounds exhibited improved green strength, modulus at 100 % elongation and bound rubber, and their vulcanizates showed synergistically improved “magic triangle” properties like obviously reduced rolling resistance and abrasion loss, and increased wet-skid resistance. It was found that the incorporation of 10 phr F-TBIR3 with CE of 60 mol% and Mw of 32 × 104 resulted in highly expected properties of the SSBR/BR/F-TBIR3 nanocomposite. The contribution mechanism of F-TBIR3 was discussed based on the improvements of polymer network structures and filler network structures. This work is expected to provide an effective strategy to construct the desired network structures for high-performance rubber composites.

Drillability Evaluation and Sensitivity Analysis of the Fencheng Formation Strata in Maye Exploration Area

Abstract Predicting drillability ratings and selecting suitable drill bits are crucial for improving drilling efficiency. This investigation employed Principal Component Analysis (PCA) to normalize adjacent well logging parameters such as natural gamma, well diameter, natural potential, and others as influencing factors and established a mathematical model for the drillability ratings of hard rock formations. A sensitivity analysis of drilling parameters for the Fencheng Formation rocks revealed that sonic time difference, formation density, natural gamma, and resistivity were closely associated with drillability ratings. Empirical results showed that a multiple logarithmic linear regression approach accurately predicted drillability ratings for hard rock formations with over 95% precision compared to experimental values. The Fencheng Formation strata’s high hardness and abrasion resistance result in poor drillability (with ratings above 7.5), with rotational speed sensitivity found to be higher than drilling pressure sensitivity for expediting drilling in hard formations. For the “turbine + PDC bit” drill tool combination, it is recommended to use a drilling pressure of 40 - 80KN and a rotary table speed of 50 - 70r/min. High rotational speeds and low drilling pressures effectively reduce bit sticking effects, while using PDC bits with turbines reduces bit wear, improving the economic efficiency of drilling operations without sacrificing mechanical drilling speed.

Enhanced abrasion resistance of NR/BR/TBIR composites through the synergistic reinforcement of carbon black and graphene oxide: Structural influence and mechanistic insights

AbstractCarbon black (CB) with different structural parameters together with graphene oxide were formed into uniformly dispersed filler network for enhancing the abrasion resistance of natural rubber/cis‐1,4‐polybutadiene rubber/trans‐1,4‐poly(isoprene‐butadiene) rubber blended composites. It showed that the CB structural parameters, such as specific surface area, surface activity and structural degree affected the formation of bound rubber. With the increase of bound rubber content, the homogeneity of filler network structure was improved and the filler‐rubber interaction was enhanced, resulting in a remarkable increase in the mechanical properties, thermal performance and abrasion resistance of the composites. Among the different types of CB, the composites filled with high‐structural‐degree CB of N134 had DIN wear volume as low as 76 mm3 and exhibited 19.5% higher abrasion resistance than N330. Wear surface observations and wear mechanism analyses showed that the increase in abrasion resistance was related to the improvement in tear resistance, hardness and thermal properties of the composites. Multiple linear regression analyses yielded that the structural degree in the structural parameters of CB had a significant correlation effect on the formation of bound rubber, and there was a strong linear relationship between the abrasion resistance of the composites and the content of bound rubber.Highlights Trans‐1,4‐poly(isoprene‐butadiene) rubber as compatibilizer for NR/BR blends. Synergistic enhancement of rubber using carbon black and graphene oxide. Carbon black with high structural degree promotes the formation of bound rubber. Described correlation between CB structural parameters and abrasion resistance of rubber.

Comparative Assessment of Compomers and Ormocers as Pit and Fissure Sealants in Permanent Molars among Children Aged 7-9 Years.

In recent years, the dental profession's focus has shifted from the therapeutic to the preventive aspect of dental caries. Pit and fissure sealants, optimal fluoridation, healthy dietary habits, and good oral hygiene have been recommended for caries prevention. Many sealant materials are available on the market. Compomers are hybrid dental materials that are modified composite resins with polyacids. The esthetic properties of traditional composite systems are combined with the fluoride-releasing and adhesive properties of glass ionomer cement (GIC). Organically modified ceramic (Ormocer) material has high abrasion resistance and better aesthetics, similar to natural teeth. To compare the sealing ability of compomer and ormocer as pit and fissure sealants in permanent mandibular first molars of 7-9-year-old children. A cross-sectional study with a split-mouth design was conducted on 88 children aged 7-9 years who attended the Department of Pediatric and Preventive Dentistry. Children were selected based on the inclusion and exclusion criteria. By tossing a coin, the placement of sealant material was selected for the right permanent first molar. Rubber dam isolation was done. The tooth surface was etched and washed. The respective sealants were applied. Sealants were cured with visible light, and occlusion was checked with articulating paper. Subsequently, the second sealant was placed in the next appointment, following the same clinical procedure in the opposite quadrant. Clinical evaluation was done at 3, 6, and 9 months for retention, marginal integrity, color match, wear, and presence of caries. The criteria were graded and rated as alpha, beta, and charlie based on modified Ryge United States Public Health Service (USPHS) criteria. All the data were statistically analyzed using Statistical Package for the Social Sciences (SPSS) software 20.0. The retention rate of ormocer at the 9-month review interval was 88.3%. There was a statistically significant difference in retention rates between compomer and ormocer (p = 0.003). The marginal integrity and wear of ormocer at the 9-month review interval were 84.4% compared with compomer, which was statistically significant with p = 0.010 and p = 0.035, respectively. Children with the fewest caries belonged to the ormocer group (p = 0.010) compared to the compomer group. Children with ormocer as a pit and fissure sealant showed good retention, remarkable marginal integrity, absence of wear, and fewer dental caries compared to compomer sealants. Hence, ormocer-based sealants can be used in pediatric dental practice to protect children's oral hygiene and promote a healthy lifestyle. Saravanan SM, Srinivasan D, AR SE, et al. Comparative Assessment of Compomers and Ormocers as Pit and Fissure Sealants in Permanent Molars among Children Aged 7-9 Years. Int J Clin Pediatr Dent 2024;17(7):742-747.

Carbonized derivatives derived from the complex of Fe/Ni bimetallic MOFs and phenolic resin for flexible piezoresistive sensors in motion capture and health monitoring

Based on the substantial high surface area and the chemical robustness inherent to metal–organic frameworks (MOFs), their integration into piezoresistive flexible pressure sensors presents significant potential. Nonetheless, the application of such sensors is impeded by the low conductivity of MOFs. In this work, we increased the conductivity of MOFs by carbonizing 2-aminoterephthalic acid iron-nickel metal–organic frameworks (Fe/Ni-MOFs) and introducing phenolic resins to protect the structure of Fe/Ni-MOFs. Piezoresistive flexible sensors were developed by embedding this carbonized derivative on the surface of PDMS films. The senrors showed a sensitivity of 198.51 kPa−1, broad operating pressure range (0–5 kPa), a fast response time (46 ms), a short recovery time (28 ms), and a high abrasion resistance. The flexible pressure device could be applied to monitor the finger motion and human pulses. Overall, these flexible high sensitivity devices demonstrate potential in the fields of wearable technologies, real-time health monitoring, and biomedical applications.

Transparent, robust, and anti-fingerprint silicone coating with a three-dimensional cross-linked network enabled by hydrosilylation reaction

Silicone coatings with anti-smudge, anti-fingerprint, abrasion resistance, and ultraviolet (UV) resistance properties are increasingly demanded for touch screens as the development of artificial intelligence and human-computer interaction interfaces. Herein, a transparent, robust, and self-cleaning silicone coating was developed by incorporating cage-like structures and long carbon chains into a 3D cross-linked network via the rational combination of polymethylhydrosiloxane (PMHS), PSS-Octavinyl substituted (VPOSS), lauryl acrylate (LA), and 1,2-epoxy-4-vinylcyclohexane (EVCH) through hydrosilylation reaction with the presence of Karstedt catalysts. After introducing sealed diphenyliodonium phosphate (I-200), the silicone coating (PVLE-I-200) demonstrated excellent pencil hardness, anti-smudge, and abrasion resistance, and its average transmittance of visible light reached about 92 %. Owing to the low surface energy carbon chains, the coating showed amphiphobic properties and excellent anti-fingerprint property. The binding between cyclohexyl epoxy and glass substrate contributed to the high adhesion of the coating, which remained nearly intact and slightly reduced surface wettability after 500 friction cycles of sandpaper. In addition, the PVLE-I-200 coating demonstrated UV resistance which could withstand 200 h of UV irradiation attributed to the cage-like structure of VPOSS. The functional silicone coating provides insights into the development of environmentally friendly coatings for touch screens with high transparency, abrasion resistance, anti-smudge, and anti-fingerprint properties.

Enhancing Durability of Concrete and Mortar with Ceramic Waste: A Comprehensive Review

The construction industry continually seeks sustainable materials to enhance the durability of structures while minimizing environmental impact. Ceramic waste, a by-product of the ceramic manufacturing process, presents a promising alternative. Traditionally used for tiles, sanitary ware, and bricks, ceramic materials are valued for their high strength, aesthetic appeal, and thermal insulation properties. The study indicates that ceramic waste enhances the durability of construction materials due to its inherent properties, such as low water absorption and high abrasion resistance. Additionally, utilizing ceramic waste addresses environmental concerns associated with landfill disposal, which include soil and water contamination, greenhouse gas emissions, and the depletion of landfill space. Incorporating ceramic waste into construction materials not only offers environmental benefits by reducing landfill waste and conserving natural resources but also provides economic advantages through cost-effective waste management and material production. This research explores the incorporation of ceramic waste into construction materials, emphasizing the enhanced durability properties like water absorption, Chloride test, UPV test, Electrical resistivity test, freezing and thawing test, drying shrinkage test and sulphate attack test of concrete and mortar mix while highlighting the dual benefits of improved material performance. The results of water absorption increases with ceramic amount increment, resistance to chloride ion rises to 20% replacement, drying shrinkage and electrical resistivity decreases with increase in amount of ceramic waste, freezing and thawing & sulphate attack showed that ceramic waste material used as aggregate increases, mass loss reduces due to freezing and thawing cycles and the amount of ceramic waste material used increases, compressive strength increases up to a certain limit when immersion in sulphuric acid solution.

Microstructure and Wear Resistance of In Situ Synthesized Ti(C, N) Ceramic-Reinforced Nickel-Based Coatings by Laser Cladding.

In recent years, laser cladding technology has been widely used in surface modification of titanium alloys. To improve the wear resistance of titanium alloys, ceramic-reinforced nickel-based composite coatings were prepared on a TC4 alloy substrateusing coaxial powder feeding laser cladding technology. Ti (C, N) ceramic was synthesized in situ by laser cladding by adding different contents (10%, 20%, 30%, and 40%) of TiN, pure Ti powder, graphite, and In625 powder. Thisestudy showed that small TiN particles were decomposed and directly formed the Ti (C, N) phase, while large TiN particles were not completely decomposed. The in situ synthetic TiCxN1-x phase was formed around the large TiN particles. With the increase in the proportion of powder addition, the wear volume of the coating shows a decreasing trend, and the wear resistance of the surface coating is improving. The friction coefficient of the sample with 40% TiN, pure Ti powder, and graphite powder is 0.829 times that of the substrate. The wear volume is 0.145 times that of the substrate. The reason for this is that with the increase in TiN, Ti, and graphite in the powder, there are more ceramic phases in the cladding layer, and the hard phases such as TiC, Ti(C, N) and Ti2Ni play the role in the structure of the "backbone", inhibit the damage caused by micro-cutting, and impede the movement of the tearing point of incision, so that the coating has a higher abrasion resistance.

Thermoplastic Vulcanizates with an Integration of High Wear-Resistant and Anti-Slip Properties Based on Styrene Ethylene Propylene Styrene Block Copolymer/Styrene Ethylene Butylene Styrene Block Copolymer/Solution-Polymerization Styrene-Butadiene Rubber.

Distinguished from traditional vulcanized rubber, which is not reusable, thermoplastic elastomer (TPV) is a material that possesses both the excellent resilience of traditional vulcanized rubber and the recyclability of thermoplastic, and TPVs have been widely studied in both academia and industry because of their outstanding green properties. In this study, new thermoplastic elastomers based on solution polymerized styrene butadiene rubber (SSBR) and thermoplastic elastomers (SEPSs/SEBSs) were prepared by the first dynamic vulcanization process. The high slip resistance and abrasion resistance of SSBR are utilized to improve the poor slip resistance of SEPSs/SEBSs, which provides a direction for the recycling of shoe sole materials. In this paper, the effects of different ratios of the rubber/plastic phase (R/P) on the mechanical properties, rheological properties, micro-morphology, wear resistance, and anti-slip properties of SSBR/TPE TPVs are investigated. The results show that the SSBR/TPE TPVs have good mechanical properties. The tensile strength, tear strength, hardness, and resilience of the TPVs decrease slightly with an increasing R/P ratio. Still, TPVs have a tensile strength of 18.1 MPa when the ratio of R/P is 40/100, and this reaches the performance of the vulcanized rubber sole materials commonly used in the market. In addition, combined with microscopic morphology analysis (SEM), it was found that, with the increase in the R/P ratio, the size of the rubber particles gradually increased, forming a stronger crosslinking network, but the rheological properties of TPVs gradually decreased; crosslinking network enhancement led to the increase in the size of the rubber particles, and the increase in the size of rubber particles made the material in the abrasion of rubber particles fall easily, thus increasing its abrasion volume. Through dynamic mechanical analysis and anti-slip tests, when the R/P ratio was 40/100, the tan δ of TPVs at 0 °C was 0.35, which represents an ordinary vulcanized rubber sole material in the market. The viscoelasticity of TPVs increased with the increase in the R/P ratio, which improved the anti-slip performance of TPVs. SSBR/TPE TPVs are expected to be used in footwear and automotive fields due to their excellent abrasion resistance and anti-slip performance.

Evaluation of Enhanced Mechanical Properties in Natural Rubber Hybrid Reinforced with Industrial Waste (Ceramic)

This study assessed the mechanical properties of hybrid composite vulcanizates made from natural rubber with ceramics industrial waste and carbon black as filler. Ceramic waste was characterized using Xray Diffraction (XRD) and Xray Fluorescence (XRF). Natural rubber (NR) was filled with ceramic powder and carbon black at varying ratios of filler loading as follow; 00, 60/00, 50/10, 40/20, 30/30, 20/40, 10/50, 0/60. The mechanical properties of the hybrid composites evaluated include; tensile strength, young modulus, Flexural Strength, Flexural modulus, Abrasion Resistance and hardness. The result obtained shows the presence of SiO2, Al2O3, Fe2O3, TiO2, CaO, MgO, Na2O, K2O in the ceramic composition and SiO2 appears to be the largest compound in the ceramic. The ceramic/CB ratio of 40/20 shows the highest tensile strength (40.00 MPa), while the modulus was highest with ratio of 60/0. The highest flexural strength (27.00 MPa) was at ceramic/CB ratio 0/60 while the lowest (19.67 MPa) was at ratio of 60/0. The flexural modulus of NR composite began to increases and peaked as the CB increases with the ceramic (40/20 pphr) filler loading at 436.33 MPa. The hardness of the hybrid composite increased as the CB concentration increased with maximum hardness obtained with ceramic/CB ratio 20/40 (47.00 shore A). At ratio of 30/30 the wearing rate was lowest (higher abrasion resistance) at 97.89, Ceramic waste can improve the mechanical properties of the natural rubber vulcanizates by increasing its elasticity, and abrasion resistance if used alone as a filler.

Effects of Preheating on the Microstructure of Laser-DED AISI 420

AISI 420 stainless steel (420 SS) is a martensitic type known for its high strength and abrasion resistance, and it is extensively used in hard-facing applications (Refs. 1, 2). However, Type 420 SS contains untempered martensite in the as-welded condition and is generally considered to have poor weldability. Successful arc welding of 420 SS requires proper preheating, post-weld heat treatment, and strict adherence to low hydrogen practices. Direct energy deposition (DED) is a fusion-based additive manufacturing (AM) process that melts metal powders to produce complex shapes and can be used for surfacing or hard-facing operations. However, as small-volume AM deposits undergo self-quenching, the cooling rate can be much faster than in welding. Consequently, the phase transformations in the AM deposit deviate further from equilibrium relative to traditional welding processes, resulting in heterogeneous microstructures and mechanical properties, potentially limiting the direct use of AM components without post-AM heat treatment (Ref. 3). Our prior work with laser-DED (L-DED) hard-facing 420 SS powder without preheat combined experiments, characterization, and kinetic modeling to rationalize the presence of remnant δ-ferrite and austenite quantitatively in room temperature microstructures. This study aimed to quantify the effects of preheating above the Ms temperature on the extent of solidification segregation and microstructures for a wall build for L-DED processing of the same heat of 420 powder. The results of the current work are contrasted with our prior study, which allows for a greater understanding of L-DED opportunities with 420 SS.

Role of Quenching Temperature Selection in the Improvement of the Abrasive (Al2O3) Wear Resistance of Hybrid Multi-Component Cast Irons.

In this paper, enhancing the tribological characteristics of novel cast metallic materials-hybrid multi-component cast irons-by applying a strengthening heat treatment is described. The experimental materials were the cast alloys of a nominal composition (5 wt.% W, 5 wt.% Mo, 5 wt.% V, 10 wt.% Cr, 2.5 wt.% Ti, Fe is a balance) supplemented with 0.3-1.1 wt.% C and 1.5-2.5 wt.% B (total of nine alloys). The heat treatment was oil-quenching followed by 200 °C tempering. The quench temperature (QT) varied in the range of 900-1200 °C, with a step of 50 °C (with a 2-h holding at QT). The correlation of the QT with microstructure and properties was estimated using microstructure/worn surface characterization, differential scanning calorimetry, hardness measurement, and three-body-abrasive wear testing (using Al2O3 particles). The as-cast alloys had a multi-phase structure consisting of primary and/or eutectic borocarbide M2(B,C)5, carboborides M(C,B), M7(C,B)3, M3(C,B), and the matrix (ferrite, martensite, pearlite/bainite) in different combinations and volume fractions. Generally, the increase in the quenching temperature resulted in a gradual increase in hardness (maximally to 66-67 HRC) and a decrease in the wear rate in most alloys. This was due to the change in the phase-structure state of the alloys under quenching, namely, the secondary carboboride precipitation, and replacing ferrite and pearlite/bainite with martensite. The wear rate was found to be inversely proportional to bulk hardness. The maximum wear resistance was attributed to QT = 1150-1200 °C, when the wear rate of the alloys was lowered by three to six times as compared to the as-cast state. With the QT increase, the difference in the wear rate of the alloys decreased by three times. The highest abrasive resistance was attributed to the alloys with 1.1 wt.% C, which had a 2.36-3.20 times lower wear rate as compared with that of the reference alloy (13 wt.% Cr cast iron, hardness of 66 HRC). The effects of carbon and boron on hardness and wear behavior are analyzed using the regression models developed according to the factorial design procedure. The wear mechanisms are discussed based on worn surface characterization.

The use of polyetheretherketone material as an occlusal splint

Occlusal splint is a treatment alternative that gives positive results in reducing the symptoms of temporomandibular diseases. This treatment involves placing an appliance made of various materials specifically for the cutting and chewing surfaces of the teeth. The most popular materials used in the construction of occlusal splints are soft and hard acrylic-based materials such as polymethylmethacrylate, ethylene vinyl acetate, polycarbonate, polyethylene terephthalate and polyetheretherketone. PEEK is a high performance, semi-crystalline, thermoplastic and thermally stable polymer belonging to the polyaryletherketone family. PEEK, which has very good dimensional stability against intraoral temperature changes, is not affected by the intraoral chemical environment. Since PEEK material is chemically stable, has high biocompatibility and abrasion resistance, its use as an occlusal splint material has become widespread today. The aim of this review is to provide information about occlusal splints produced using PEEK material and digital procedures, which are becoming increasingly popular in dentistry, and to contribute to the literature.

Microstructure and Erosion Wear of In Situ TiC-Reinforced Co-Cr-W-C (Stellite 6) Laser-Cladded Coatings.

The article presents research results on the possibility of shaping the structure and properties of Co-Cr-W-C-Ti alloys (type Stellite 6) using laser cladding technology. Cobalt-based alloys are used in several industries because they are characterized by high erosion, abrasion, and corrosion resistance, retaining these properties at high temperatures. To further increase erosion resistance, it seems appropriate to reinforce material by in situ synthesis of hard phases. Among the transition metal carbides (TMCs), titanium carbide is one of the hardest and can have a positive effect on the extension of the lifetime of components made from cobalt-based alloys. In this article, concentration of C, W, and Ti due to the possibility of in situ synthesis of titanium carbides was subjected to detailed analysis. The provided research includes macrostructure and microstructure analysis, X-ray diffraction (XRD), microhardness, and penetrant tests. It was found that the optimal concentrations of Ti and C in the Co-Cr-W-C alloy allow the formation of titanium carbides, which significantly improves erosion resistance for low impact angles. Depending on the concentrations of titanium, carbon, and tungsten in the molten metal pool, it is possible to shape the alloy structure by influencing to morphology and size of the reinforcing phase in the form of the complex carbide (Ti,W)C.

A Comparative Study of Dry Turning Performance of 4340 Alloy Steel with As-Received and Cryogenically Treated Coated Cermet Cutting Tools

Cryogenic treatment has been shown to significantly improve the cutting performance of inserts. Alloy steel grade 4340, renowned for its high impact and abrasion resistance, has extensive application in aircraft landing and high-power transmission gears. In this study, a comparative characterization (microhardness and XRD profile) and dry turning performance evaluation (turned surface roughness and insert wear) of alloy steel grade 4340 were performed using as-received and cryogenically treated coated cermet cutting inserts. The turning operation was carried out with various cutting velocities ( 55, 90, and 150 m/min) and a constant feed and cutting depth (0.111 mm/rev and 1 mm) under dry cutting conditions. The cryogenically treated insert obtained A reduced Ra value compared to untreated conditions at all cutting speeds. In addition, Ra value was reduced to a maximum of 29%. A lower level of insert wear and chip particle deposition at the cutting point was observed with cryo-treated inserts. Finally, it was revealed that the better machining characteristics in terms of reduced Ra values and insert wear with cryo-treated conditions were due to the enhanced wear resistance over the untreated conditions.

Influence of Yarn and Fabric Properties on Mechanical Behavior of Polymer Materials and Its Retention over Time.

The mechanical properties of textile materials play a crucial role in determining their comfort, functionality, performance, safety, and aesthetics. Understanding and optimizing these properties is essential to meet consumer demands. Key aspects of mechanical properties, such as surface roughness, abrasion resistance, and compression, have a significant impact on the touch and durability of the material, as demonstrated by various research studies. This study focuses on analyzing the mechanical properties of materials produced of different polymer yarns and their changes under combined aging factors. The findings emphasize the significance of textile abrasion resistance and surface roughness measurement, particularly for aged materials. Although the use of recycled polyester yarn is sustainable and offers advantages such as higher tensile strength, the results have shown that the use of conventional polyester yarn is more advantageous overall as it has higher abrasion resistance, a smoother surface texture, and better elasticity retention after aging. The insights presented are vital for designing high-performance sportswear, which is crucial in today's competitive environment.