Poor Abrasion Resistance Research Articles

Preparation of Durable Polytetrafluoroethylene Superhydrophobic Surfaces by Hot Embossing Technique

ABSTRACTIn this paper, the surface microstructure of screen meshes with different mesh sizes is processed onto the polytetrafluoroethylene (PTFE) surface using a micro‐nano thermal imprinting technique. Simultaneously, silica microspheres are coated on the screen mesh. After hot embossing, these microspheres adhere to the PTFE surface, enhancing its superhydrophobicity and addressing issues such as shallow microstructure, poor abrasion resistance, and reduced hydrophobicity over prolonged use. Through several comparative experiments, the optimal processing conditions, including temperature, pressure, heating time, mesh aperture, and material thickness, were determined by measuring the contact angle and observing the microstructure. The experimental results indicate that the maximum hydrophobic angle of the PTFE surface is 154°, and the addition of silica microspheres significantly improves the superhydrophobicity and weatherability of the PTFE.

Robust superhydrophobic copper oxide layer with high-low staggered structure on polymers for strong anti-icing and all-day de-icing

Recently, superhydrophobic materials with photothermal and electrothermal conversion functions have received much attention in solving icing problems. However, the currently emerging methods still suffer from the complexity of the preparation method, poor hydrophobicity, or poor abrasion resistance. Herein, a robust copper oxide layer with a high-low staggered structure was prepared on the polymer surface by laser-induced selective metallization (LISM), which can be used for anti-icing and all-day (daytime and night) de-icing. The high-low staggered structure of the superhydrophobic copper oxide surface gives the surface excellent hydrophobicity, light trapping capability, and high electrical resistance, resulting in the surface with superior delayed icing, photothermal de-icing, and electrothermal de-icing capabilities. The copper oxide layer has a water contact angle (CA) of up to 161.3° and a surface delayed icing time of 1374 s, which is 8.23 times longer than the conventional copper layer prepared by LISM. In addition, the surface temperatures of the copper oxide layer are 67.6 °C and 57.3 °C, respectively, under 1.0 sun irradiation or at 5 V applied voltage. Under these conditions, the copper oxide surface’s photothermal and electrothermal de-icing times are 159 and 186 s. In addition, the high-low staggered structure of the prepared superhydrophobic copper oxide surface makes the surface less susceptible to abrasion, resulting in excellent mechanical robustness of the copper oxide layer surface. The proposed method is suitable for low-cost large-scale manufacturing, which guides the preparation of copper oxide superhydrophobic materials for anti-icing and all-day de-icing, and has good application prospects.

Investigation of the microscopic damage mechanisms in cotton fibers induced by mechanical friction

For the problem of friction damage in cotton fiber processing, a multi-scale combination of investigation methods is proposed. The surface of damaged cotton fiber is detected by relevant test means with damage features such as dislocations, defects and cracks. The internal pyranose ring and glycosidic bond fail, the crystallinity decreases, and the number of hydrogen bonds decreases. Anisotropy exists in the frictional properties of the microscopic surface of the cotton fiber. The results of molecular dynamics simulation showed that the cellulose main chain failed mainly at the glycosidic bond, and the side chain failed mainly at the hydroxymethyl functional group. Its interchain hydrogen bond O3H…O5 was the least damaged. The cellulose crystal (200) surfaces had poor abrasion resistance, and the frictional properties of each crystal surface were anisotropic. The results of the study provide a theoretical basis for improving friction and wear problems in cotton fiber processing.

Negative expansion induced anti-abrasive self-cleaning coatings for enhancing output of solar panels

Pollutants on solar panels impede sunlight absorption, leading to a reduction in their output power. Superhydrophilic coatings exhibit effective self-cleaning performance as droplets fully spread on their surfaces. However, one challenge for the commercial development of transparent superhydrophilic coatings is poor abrasion resistance. Frictional heating on the coatings’ surface causes the abrasion force to rise uncontrollably, which in turn causes the coatings to either fracture or wear catastrophically. A promising alternative is utilizing novel adaptive materials with a negative thermal expansion coefficient in the coating. The compressive stress on the surface of the coating with negative expansion will enhance its abrasion resistance. Here, we demonstrate a method to achieve compressive stress in the coating by incorporating halloysite (HNTs) nanotubes due to their negative expansive behavior. Hydrolyzed tetraethyl orthosilicate (TEOS) combines HNTs nanotubes with SiO2 nanoparticles, thus forming a hard nano-composite unit. Meanwhile, amino resin and acrylic resin as adhesives participate in constructing the coating’s three-dimensional network structure. The surfactant sodium alkenyl sulfonate (AOS) endows the coating with superhydrophilicity. As a result, the nano-composite (NC) coating shows superior superhydrophilicity and anti-abrasive properties. The NC coating retains good hydrophilicity and self-cleaning properties after 2000 cycles of Taber abrasion loading 250 g or 1000-line cycles of steel wool friction loading 500 g. The self-cleaning performance of the robust NC coating on solar panels can improve the output power by up to 33.65 % after 296 days. Hence, introducing shrinkage components such as HNTs may provide a general strategy for developing robust superhydrophilic coatings.

Influence of ultrasonic power modulation on the optimisation of aluminium alloy micro-arc oxidation coating properties

Conventional micro-arc oxidation (MAO) technology, due to the randomness and transient nature of arc discharge, produces coatings with numerous defects, poor abrasion resistance, and inadequate ability to effectively block the intrusion of corrosive media. In this paper, ultrasonic-assisted technology was used to study the effect of different ultrasonic power regulation on the performance optimization of MAO coating on 6061 aluminum alloy. The coating microstructure and elemental composition were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer, and its hardness, wear resistance, corrosion resistance and other properties were tested. The results show that the prepared coating has the characteristics of high hardness, good wear resistance and excellent corrosion resistance under the assistance of ultrasonic power of 50 W. This is mainly attributed to the cavitation effect, mechanical effect and thermal effect generated by the corresponding ultrasonic power, which effectively enhances the surface quality, performance and service life of the coating. This study provides valuable insights into the interaction between ultrasound power and the resulting MAO coatings, and has important implications for optimizing ultrasound-assisted processes and improving coating properties.

Improvement in the corrosion and wear properties of monel 400 alloy by electroless Ni-P deposition in seawater

Monel 400 alloy has been generally applied to marine equipment because of their outstanding corrosion resistance. However, poor abrasive resistance limits its service life. Herein, by depositing electroless Ni–P on Monel 400 alloy, the abrasive resistance after corrosion and wear tests and cathodic protection tests improved by 5 and 21 times, respectively. In addition, due to the inhibiting effect of the corrosion products of nickel and phosphorus, the corrosion resistance of the deposition is better. Ni–P deposition at 500 °C is more beneficial for improving the corrosion resistance and abrasive resistance of the alloy. More interestingly, the synergy between corrosion and wear of the alloy changes from inhibiting to promoting effects after Ni–P deposition.

Zinc oxide bridges the nanofillers to enhance the wear resistance and stability of triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) have received widespread attention as a means of harvesting mechanical energy from the environment and converting it into electricity. As people continue to explore the field of infinite sensors, traditional TENGs have faced persistent challenges in practical application, mainly due to the poor abrasion resistance and stability of the existing polymers commonly used. Herein, the polyphenylene sulfide (PPS) was melt blended with liquid crystal polymer (LCP) to be used as matrix, and the interfacial bonding strength between the matrix and filler was improved by zinc oxide (ZnO) grafted carbon nanotubes/graphene oxide (CNTs/GO). Under friction conditions of 100 N load and 0.5 m/s, the friction coefficient and wear rate of resultant nanocomposites were significantly reduced to 0.2 and 2.09 × 10-5 mm3/N, respectively. The abrasion resistant TENG (AR-TENG) was fabricated based on 0.3ZnO/CNTs/GO/LCP/PPS exhibited outstanding electrical output performance, which was attributed to the high dielectric constant of 5.3, improved surface roughness and interfacial contact area of composites. Consequently, this study reported a novel approach to tailor AR-TENG into a highly abrasion resistant and stable sensor. This customization enabled the AR-TENG to operate reliably in harsh environments (high temperatures and humidity), thereby expanding its potential applications.

Surface property enhancement of impregnated paper decorative panel by MUF-polyelectrolyte complex@Nano-Al2O3 blending

The surface properties of melamine-urea-formaldehyde (MUF) impregnated paper decorative panels are unsatisfactory, characterized by brittle surfaces, poor abrasion resistance, and limited flame retardancy. A modification was introduced to the MUF resin by incorporating a blend of polyelectrolyte complex polyethyleneimine (PEI)-phytic acid (PA) and Nano-Al2O3 with the aim of enhancing the surface properties of the decorative panel. The modified resin underwent characterization, and subsequent analyses were conducted to investigate the properties of both the modified impregnated paper and the decorative panel. The results showed that the thermal stability of the modified resin was improved with a curing temperature of 124 °C. In comparison to the control, the modified impregnated paper showed an increase of 146.0 % in tensile strength and 154.5 % in elongation at break. The improved toughness of the modified MUF-impregnated paper resulted in a notable upsurge in both surface bond strength and cracking resistance of the decorative panel. The combustion test results indicated that the modified impregnated had a LOI value of 40.0 % and self-extinguishing behavior. In addition, due to the inclusion of Nano-Al2O3, the decorative panel exhibited a low abrasion value of only 14.1 mg/100r. Overall, the technology proposed in this study can improve the surface properties of decorative panels, increase their added value, and provide a new strategy for modifying MUF resin in the impregnated paper-decorated wood-based panels industry and for researchers.

A Study on the Properties of Composite Modified Mortar with Styrene-Butadiene Rubber Latex and Silica Fume.

To solve the problem of the poor abrasion resistance of concrete pavement surface mortar, this study substituted cement with equal amounts of styrene-butadiene rubber (SBR) latex and silica fume (SF) to investigate the effects of organic/inorganic material composite modification on the fluidity, drying shrinkage, mechanical properties, and abrasion resistance of cement mortar. Also in this study, the microstructure, product, and pore structure characteristics of the composite modified cement mortar were investigated using scanning electron microscope (SEM), X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and the Brunauer-Emmett-Teller (BET) method. This research found that the sole substitution of SF negatively impacted the mortar's fluidity and drying shrinkage yet enhanced its mechanical strength and abrasion resistance; the incorporation of SBR latex improved fluidity, reduced shrinkage, and increased flexural strength but adversely affected the compressive strength of the mortar. Additionally, the enhancement of the mortar's abrasion resistance with SBR latex was significantly greater than that with SF. When SBR latex and SF were used together as substitutes, the latex struggled to offset the negative impact of SF on mortar fluidity but effectively reduced shrinkage; SF compensated for the detrimental effect of the latex on compressive strength. Moreover, the primary role in enhancing the mortar's abrasion resistance was played by the latex. Microscopic tests showed that SBR latex and SF could increase the content of calcium silicate hydrate (C-S-H) gel, inhibit the formation of ettringite (AFt) and reduce carbonation, refine the pore size of cement mortar, and effectively improve the microstructure of mortar.

Fabrication of bulk superhydrophobic wood by grafting porous poly(divinylbenzene) to wood structure using isocyanatoethyl methacrylate.

Superhydrophobic treatment of wood can effectively reduce the interaction between wood and moisture, avoiding deformation, cracking, mould, and other defects caused by water absorption, which can extend the service life of wood and broaden the application field. Currently, the poor abrasion resistance of superhydrophobic wood is a crucial problem limiting its widespread application, and the preparation of superhydrophobic wood with robustness, abrasion resistance, and chemical resistance remains a huge challenge. In this work, robust bulk superhydrophobic wood with excellent abrasion resistance and chemical durability was fabricated by synthesizing porous poly(divinylbenzene) in wood cell cavities using graft copolymerization and solvothermal methods. The contact angles and rolling angles on the superhydrophobic wood surface were approximately 156° and 3°, respectively. Superhydrophobicity was carried through the entire structure of the wood. Even after severe damage by abrasion and sawing, as well as tests with organic solvents and harsh environments, the superhydrophobic properties of wood remained stable. Meanwhile, the superhydrophobic wood exhibited great self-cleaning and antifouling properties. In addition, the water uptake and dimensional stability of the wood were significantly improved. This work developed a simple, efficient, and durable strategy for the fabrication of superhydrophobic wood with robustness, abrasion resistance, and chemical resistance, which was expected to be applied to the wood industry to achieve the high-value applications of wood products and extend their service life.

Investigation on roller-type ultrasonic assisted magnetorheological finishing for biomedical small and complex surface of titanium alloy

Biomedical small workpieces made of titanium alloys are widely used in orthopedic implants. However, the poor abrasive resistance and the complex shape of the parts with small size could seriously reduce its finishing quality and efficiency. In this study, a roller-type ultrasonic assisted magnetorheological finishing (R-UMRF) for biomedical small and complex surface of titanium alloy was proposed. The R-UMRF principle was illustrated in detail. Then, the magnetic circuits of R-UMRF with three-pole electromagnet excitation device was designed and mathematical expressions of magnetic flux density in the MR fluid polishing region was further established. Moreover, simulation analysis of the designed magnetic circuit was performed as well. An experimental prototype was fabricated and tested to the feasibility of the developed MR polishing fluid and R-UMRF device. The results showed that the surface roughness decreases with the increase in spindle speed and roller speed, however, it first decreases and then increases with the increase in ultrasonic amplitude and the applied current. In addition, the surface roughness change rate increases with the increase in spindle speed and roller speed, however, it first increases and then decreases with the increase in ultrasonic amplitude and the applied current. The optimized process parameters for the titanium alloy screws are the MR polishing fluid of MRPF-2, the spindle speed of 240 r/min, the roller speed of 110 r/min, ultrasonic amplitude of 10 µm, and applied current of 4 A. The surface roughness Ra of 0.089 µm can be obtained after 140 min finishing under the optimized parameters. R-UMRF is an adaptable and efficient method for finishing small and complex surface of titanium alloy.

Self‐lubricating epoxy composite coating with linseed oil microcapsule self‐healing functionality

AbstractCured epoxy resins have poor abrasion resistance, which shortens the service life of the material. This work aims to improve the tribological properties of epoxy resins by coupling self‐lubrication and auto‐healing. In this study, linseed oil microcapsules with an average particle size of 38.57 μm and good thermal stability were successfully prepared by in situ polymerization. The effects of microcapsule content on the tribological, mechanical, and self‐healing properties of the composite coatings were studied. It was demonstrated that the composite coating has outstanding self‐lubricating properties. The coefficient of friction reduced from 0.634 (pure epoxy resin) to 0.0459 (epoxy resin with 10 wt.% linseed oil microcapsules). Wear rate reduced from 7.16 × 10−4 mm3/(N m) to 1.74 × 10−5 mm3/(N m). The self‐lubricating mechanism of the coating was investigated by SEM and EDS, which indicated that the formation of uniform and continuous lubricating film on the surface of the friction pairs was the key to improving the wear resistance of the material. In addition, the linseed oil released after the microcapsules rupture can repair the abrasion marks by reacting with oxygen during the friction process. The dual‐functional effect of linseed oil microcapsules prolongs the life of epoxy resin coating and expands its application range.

Double-Glow Plasma Surface Alloying of BTi-62421S Alloys: Regulation of Microstructure Properties

In order to meet the design requirements of lightweight artillery and adopt the method of double-glow plasma nitriding to solve the problem of low hardness and poor abrasion resistance of Ti alloy, the BTi-62421S high-performance titanium (Ti) alloy was selected as the experimental material to replace gun steel. To study the effect of different nitrogen (N) concentrations on the heat resistance scouring performance of BTi-62421S high-performance Ti alloy and investigate the influence of alloying elements on the heat resistance scouring performance under the same parameters compared with the commonly used TC4 Ti alloy, argon was used as the protective gas by continuously increasing the N concentration (Ar/N2 = 1:1, 1:2, 1:3). It was found that the honeycomb structure on the surface of the sample and the thickness of the coating increased continuously, reaching a thickness of 15 μm, while the depth of the nitride particles extending from the coating to the substrate also increased, reaching a maximum depth of 26 μm. The orientation of TiN changed from 37° to 62°. The hardness of the coating showed a negative correlation with the coefficient of frictional abrasion, which significantly improved the heat-resistant scouring performance of BTi-62421S high-performance Ti alloy.

Multifunctional composite coatings with hydrophobic, UV-resistant, anti-oxidative, and photothermal performance for healthcare

Personal protective textiles have attracted extensive interest since Corona Virus Disease 2019 has broken out. Moreover, developing eco-friendly, multifunctional waterproof, and breathable surface is of great importance but still faces enormous challenges. Notably, good hydrophobicity and breathability are necessary for protective textiles, especially protective clothing and face masks for healthcare. Herein, the multifunctional composite coatings with good UV-resistant, anti-oxidative, hydrophobic, breathable, and photothermal performance has been rapidly created to meet protective requirements. First, the gallic acid and chitosan polymer was coated onto the cotton fabric surface. Subsequently, the modified silica sol was anchored on the coated cotton fabric surface. The successful fabrication of composite coatings was verified by RGB values obtained from the smartphone and K/S value. The present work is an advance for realizing textile hydrophobicity by utilizing fluorine-free materials, compared with the surface hydrophobicity fabricated with conventional fluorinated materials. The surface free energy has been reduced from 84.2 to27.6 mJ/m2 so that the modified cotton fabric could repel the ethylene glycol, hydrochloric acid, and sodium hydroxide solutions, respectively. Besides, the composite coatings possesses lower adhesion to deionized water. After 70 cycles of the sandpaper abrasion, the fluorine-free hydrophobic coatings still exhibits good hydrophobicity with WCA of 124.6 ± 0.9°, with overcoming the intrinsic drawback of the poor abrasion resistance of hydrophobic surfaces. Briefly, the present work may provide a universal strategy for rapidly creating advanced protective coatings to meet personal healthcare, and a novel method for detecting RGB values of composite coatings by smartphone.

Transparent superhydrophilic composite coating with anti-fogging and self-cleaning properties

Superhydrophilic coatings have incomparable advantages in anti-fogging and self-cleaning but are limited to poor abrasion resistance and water resistance. Consequently, the research on the contradiction between hydrophilicity and water resistance, as well as abrasion resistance and visible transmittance, has become a focus of superhydrophilic coatings. Herein, we design a ceramic-polymer superhydrophilic composite coating with a high density, strong cross-linking structure, and smooth surface. Because of its static water contact angle (WCA = 3.2°) and short water spreading time (ST = 1878 ms), the transparent composite coating exhibits anti-fogging performance. Meanwhile, it exhibits anti-fogging durability even after 400 Taber abrasion cycles under a 250 g load or immersion in boiling water for 30 min. Furthermore, the result of self-cleaning characterization and theoretical analysis demonstrate that the low surface roughness endows the composite coating with excellent self-cleaning properties. The composite coating can effectively scavenge oil and dust pollution on its surface in a humid environment. Thus, the developed composite coating in this work is potential in the anti-fogging and self-cleaning fields.

Improved Adhesion Strength for Electrodeposited Nickel Onto Titanium Alloys Via the Brush Plating Method

Titanium and titanium alloys are attractive materials in a variety of industries such as aerospace due to a high strength to weight ratio and a surface which is naturally resistance to many forms of corrosion. However, tribological properties such as poor abrasion resistance and high friction during metal-to-metal contact have proven difficult to handle without additional treatments. Application of coatings onto the material’s surface is one means of protecting it from those poor tribological properties.Electroplated nickel coatings retain much of the corrosion resistance desired of titanium alloys while also exhibiting better abrasion and wear resistance. Electroplating onto titanium and its alloys is prohibitively difficult due to the propensity of the material to form a tenacious oxide coating on any fresh surface instantaneously after its exposure. The oxide surface acts as a barrier between the solution and the titanium surface reducing the adhesion strength of the resulting deposit. The oxide layer is most commonly removed and the surface modified by hydrofluoric acid (HF) based treatments. HF is considered highly dangerous to workers and to the environment and work is being done to heavily limit its use.For this work, a proprietary chloride-based solution was used during the preparatory steps. Brush or selective plating was chosen as the application technique due to its ability to perform the entire operation with the substrate exposed to solution and under potential control. In most applications of electroplating, the surface/part to be plated must be transferred between multiple tanks containing each preparatory solution used to etch and activate the surface which would involve exposure to air at several points. In addition, the brushing action inherent in brush or selective plating creates a surface environment which can be optimized to promote strong adhesion at the nickel/titanium interface.This presentation will discuss how SIFCO’s brush plating process technology and automation capabilities were used to achieve strong adhesion to the titanium surface without the use of HF. Focus was specifically placed on achieving strong adhesion of a nickel pre-plate onto the titanium surface which allows for a multitude of other coatings to be applied thereafter. The method was performed using a single anode through which the solutions for each step flowed. The samples were under applied potential and immersed in solution throughout the entire process. Applied potential and solution delivery were automated to maximize process consistency.Samples were measured for tensile adhesion strength via the specification ASTM C633. Several variables related to the preparatory procedure were optimized during the study including the flow rate of the solution, the voltage/current conditions, and the evaluation of preparatory steps taken before the electrochemical procedure.

Effects of electrophoretic deposited graphene coating thickness on the corrosion and wear behaviors of commercially pure titanium

Ti and its alloys have been exploited in various industrial sectors owing to its unique combination of properties. However, their poor corrosion and abrasion resistance behaviors lead to failure of industrial components. So, the purpose of this study is to improve both electrochemical and tribological properties of cp-Ti (Grade 2) by graphene coatings obtained through an elec- trophoretic deposition technique (EPD). In this study, two deposition times of 5 and 20 min were selected to examine the influence of coating thickness on coating properties. The surface morphology, phase purity, surface rough- ness, structure and adhesion strength of graphene coatings were investigated. The corrosion and wear resistance properties of bare Ti and graphene coat- ings were evaluated using electrochemical workstation and reciprocating type ball-on-plate tribometer respectively. The results revealed that the smooth and compact microstructure of thin graphene coating of thickness 2.16 μm ex- hibited superior corrosion resistance and lubricating properties (COF = ~0.02) compared to thick graphene coating of thickness 11.8 μm (COF = ~0.17).This may be ascribed to higher density of defects in terms of micro-porosities and voids in case of thick coating compared to that of thin coating which resulted in reduced barrier effect against corrosive solution and slight increment in its COF value. However, thick graphene coating displayed higher durability of its lubricity behavior and good wear resistance property due to the presence of less residual stress compared to thin graphene coating as characterized by X-ray diffraction analysis. Nevertheless, both graphene coatings demonstrated significant improvement in both corrosion and wear resistance properties of bare Ti substrate, thereby acting as a potential candidate to be used as a coating material for various industrial applications.

Tree root-inspired robust superhydrophobic coatings with high permeation for porous structures

SummarySuperhydrophobic coatings have tremendous potential for protecting porous structures from corrosion. However, the weak adhesion and poor abrasion resistance have long been challenges for their real-life applications. Inspired by tree roots, we prepared a robust superhydrophobic coating by spraying fluorinated nanodiamonds (FNDs) on a permeable epoxy coating. The epoxy can not only coat the surface but also permeate deeply inside a porous substrate and consolidate in situ as tree roots in soil. Thus, the structure is thoroughly reinforced where the pull-off strength reaches 9.4 MPa for concrete. On the other hand, the surface is covered with immobilized FNDs, forming a superhydrophobic surface. Thanks to the ultra-hard FNDs, the coating surface has high abrasion resistance and its superhydrophobicity holds even after 100 abrasion cycles. Moreover, it exhibits self-cleaning, anti-icing, and anticorrosion performance. It is promising in protecting various porous structures such as concrete, wood, and untreated corroded steel.

Corrosion Behaviour of Cu/Carbon Steel Gradient Material

Research on improving the corrosion resistance of carbon steel has become a hot topic in the iron and steel field in recent years. Copper plating on the surface of carbon steel is considered an effective means to improve its corrosion resistance, but the copper-plated carbon steel material prepared by this method has the problems of poor abrasion resistance, easy delamination of copper layer and similar issues, which affect the service performance of the copper-plated carbon steel material. To solve this problem, a new type of material whose surface is copper and the copper element is gradually diffused into carbon steel was developed by a plating-diffusion method, which is defined as a copper-carbon steel gradient material. Carbon steel with a copper plated surface and the Cu-Fe/carbon steel gradient material with 80% Cu content on the surface were prepared by the same method. The cross-sectional microstructure and composition of different samples were analysed, and the corrosion behaviors of samples in 3.5% NaCl solution were studied by the linear polarization curve method and electrochemical impedance spectroscopy. The cross-sectional microstructure result shows that the diffusion of copper in carbon is mainly carried out along its grain boundary, and the diffusion of copper will inhibit the growth of grains during heat treatment. As shown in the results of corrosion behaviors, there is no pitting corrosion in the corrosion process of all samples, as well as the stable passive film. All samples showed active dissolution. Compared with carbon steel, the corrosion potential of the Cu/carbon steel gradient material becomes more positive from −600 mV to −362 mV, the corrosion current density decreases from 53.0 μA/cm2 to 30.6 μA/cm2 and the radius of electrochemical impedance spectroscopy enlarges while the corrosion resistance is improved, and the corrosion resistance is mainly obtained by its surface copper layer. The corrosion resistance of Cu-Fe/carbon steel gradient material is lower than that of Cu/carbon steel gradient material, while it is still better than carbon steel, and it shows a clear passivation trend during corrosion. Therefore, the copper/carbon steel gradient material can significantly improve the corrosion resistance of carbon steel. Even after the surface copper layer is destroyed, the gradient material can protect the matrix and improve the service life of the material.

EFFECT OF EMULSION SBR PREPARED BY ASYMMETRIC REVERSIBLE ADDITION-FRAGMENTATION TRANSFER AGENT ON PROPERTIES OF SILICA-FILLED COMPOUNDS

ABSTRACT The development of ultra-high-performance tires that satisfy fuel efficiency, traction, handling performance, and abrasion resistance has gained significant importance in the tire industry. Solution SBR has been used as a raw material, owing to its useful characteristics (e.g., narrow dispersity controllable microstructure and chain-end functionalization). In a recent improvement, emulsion SBR (ESBR), a high-molecular-weight compound with narrow dispersity, has been reported for application in the tire tread compounds. In particular, S,S-dibenzyl trithiocarbonate (DBTC) reversible addition-fragmentation transfer (RAFT) ESBR has exhibited excellent abrasion resistance and fuel efficiency in unfilled and carbon black–filled vulcanizates. However, owing to the symmetrical structure of DBTC RAFT ESBR, the polymer chain was shortened by the reaction of a silane coupling agent with trithiocarbonate, leading to poor abrasion resistance and fuel efficiency in the case of silica-filled vulcanizates. In this study, benzyl (4-methoxyphenyl) trithiocarbonate (BMPTC), an asymmetric RAFT agent that promotes unilateral polymer growth, was synthesized and used in the polymerization of BMPTC RAFT ESBR. Chain cleavage was not observed. Upon application to silica-filled vulcanizates, BMPTC RAFT ESBR exhibited improved abrasion resistance (by 9%), improved fuel efficiency (by 20%), and improved wet traction performance (by 10%) compared with the DBTC RAFT ESBR.