Abrasion Test Research Articles

Titania nanoparticles finishing for smart leather surface

This study focuses on the synthesis and characterization of nanoparticles, specifically titanium dioxide (TiO2) with a uniform size of approximately 5–8 nm in diameter. The nanoparticles exhibit high dispersibility and stability in hydrophilic environments. Notably, nitrogen-doped nanoparticles demonstrate intriguing self-cleaning properties, as evidenced by the degradation of methylene blue stain under UV light. Rutile nanoparticles stabilize color and color fastness in the presence of anatase-covered surfaces. Anti-mold tests reveal enhanced antimicrobial properties of the surfaces containing titania NPs when functionalized with polyethylene glycol (PEG). Ascorbic acid functionalized nanoparticles show promising behavior, encouraging the exploration of nanoparticle functionalization for property improvement. Leather samples coated with nanoparticles undergo abrasion, wear, and scratch resistance tests. The nanoparticles significantly enhance abrasion resistance, doubling the resistance. This suggests the potential for nanoparticle-based finishing to improve fastness to dry and wet rubbing, reducing defects in the coating.

Superhydrophobic finishing of cotton fabric via nonsolvent-induced phase separation of polystyrene–perfluoropolyether block copolymer

This paper reports synthesis of polystyrene–perfluoropolyether block copolymer@cotton fabric (PS–PFPE@CF) with a rough structure through nonsolvent-induced phase separation. The factors affecting the hydrophobicity of the coating, such as solvent quality, the molecular weight of the PS segments, and the volume ratio of tetrahydrofuran/1,3-di(trifluoromethyl)benzene (THF/DTFMB) and THF–MeOH, were all investigated, and the relation between the coating structure and hydrophobicity was also analyzed. In the THF–DTFMB system, PS–PFPE@CF (4 h, 80 mg/mL) appeared as a secondary structure with the superposition of small spheres on large spheres. For this structure, the water-contact angle reached 156.2° ± 0.5° and the sliding angle was 9.5° ± 1.5°. Furthermore, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and thermogravimetric analysis confirmed that PS–PFPE coated the cotton fabric. Finally, application tests were performed to assess the application prospects of PS–PFPE@CF. Oil-water separation, self-cleaning, and antifouling applications were studied, and the experimental results showed that the separation efficiency of the superhydrophobic fabric was nearly constant, from 99.4 % to 98.3 % after 10 oil-water separation tests. PS–PFPE@CF exhibited excellent self-cleaning properties and performed well in the sandpaper abrasion and tape peeling tests. This research thus used a degradable PFPE block copolymer to produce cotton fabrics with excellent hydrophobicity, self-cleaning, and wear resistance.

Performance of compressed earth bricks reinforced with sugar industrial by-products bagasse and molasse: Mechanical, physical and durability properties

Because sustainable development is a major concern, many studies focus on reducing greenhouse gas emissions during the manufacturing of building materials. Therefore, in this study, we aim to produce lightweight eco-friendly compressed earth bricks (CEB) using industrial sugar by-products, sugarcane bagasse fibers (SCB) and molasse (SCM), as soil stabilizers to diminish the employment of cement. First, we investigated the physical, chemical, and mineralogical composition of the sugar by-products and the used soil. Then, we produced three types of CEB: bricks with soil and SCM (5 wt% and 10 wt%), bricks with soil and SCB (0.5 wt%, 0.75 wt%, and 1 wt%), and bricks with soil, SCB and SCM (this mixture considered two variable parameters: 5 wt% and 10 wt% of SCM, with varying SCB concentrations at three distinct levels: 0,5 wt%, 0.75 wt% and 1 wt%).The results showed that the incorporation of SCM as a stabilizer instead of cement in CEB enhanced both the dry and wet compressive strength, reaching 11.128 MPa and 9.897 MPa, respectively, which represent more than three times the results for the reference soil brick. As to the soil-SCB matrix, the incorporation of SCB decreased the compressive strength by about 36 % (from 3.338 MPa corresponding to reference brick composed only with soil to 2,142 MPa related to bricks stabilized with 1 wt% of SCB). Finally, for the composite soil-SCB-SCM, the highest value obtained was 9.309 MPa related to 10 wt% of SCM and 0.5 wt% of SCB. Moreover, the durability properties including dry abrasion, erosion, and capillarity tests were investigated and compared. The results indicated that SCM has satisfactory durability criteria while bricks stabilized with only SCB showed low resistance, especially to the capillarity test.

Calorimetry of amorphous calcium carbonate is correlated with its lithification and durability as synthetic stone—implications for CO2 storage and utilization

The properties of amorphous calcium carbonate (ACC) and its transformations to crystalline polymorphs are frequently studied in aqueous systems and in small quantities. In this study, synthetic calcium carbonate stones are created from bulk ACC and crystalline polymorphs, which were precipitated from gaseous CO2, at a gradient of end pH. Some of the ACCs hardened into stones which are durable against an abrasion and impact test, while some of the ACCs create fragile, friable stones. When ACCs which transform to durable stones and those which transform into fragile stones were subject to calorimetry, significant differences were observed. These stones, synthesized from gaseous CO2, can be used as a storage reservoir for utilized CO2 in construction and other infrastructure applications.

Effect of TiO2 Nanofillers on the Mechanical and Abrasive Wear Properties of Epoxy Reinforced with Carbon Fabric Hybrid Composites.

Recent studies show that nanofillers greatly contribute to the increase in the mechanical and abrasive behaviors of the polymer composite. In the current study, epoxy composites were made by hand lay-up with the reinforcement of carbon fabric and titanium dioxide (TiO2) nanoparticles as secondary reinforcement in weight percentages of 0.5, 1.0, and 2.0. Hardness, tensile, and abrasive wear tests have been carried out for the fabricated composites. The obtained results confirm that as the percentage of filler addition increases, hardness of the carbon epoxy (CE) composite increases, and significant enhancement of 10.25% hardness is confirmed in 2 wt % nano TiO2-added CE composite. The CE composite filled with 2 wt % of TiO2 nanofiller shows 15.77 and 9.15% improvement of tensile strength and modulus, respectively, compared to unfilled CE composites. The abrasive wear volume exhibits a nearly linear increasing trend as the abrading distance increases. In addition, it is discovered that the abrasive wear volume is greater for higher applied loads. The inclusion of nano TiO2 reduced the wear loss in the CE composite for all abrading distances, regardless of the load, low or high. The scanning electron microscopy analysis of worn surfaces was carried out to analyze the contribution of the filler to improve the wear resistance.

Formation of Highly Robust Superhydrophobic Nanocomposite Coatings via Dual Spraying Technique

The development of materials that repel water, known as superhydrophobic materials, has been hindered by their vulnerability to mechanical abrasion. This issue is particularly pronounced for superhydrophobic nanocomposite coatings fabricated using a simple blend of resin and nanoparticles (NPs) through uncomplicated methods such as spraying or brushing, where an excessive amount of NPs can deteriorate the mechanical property. Moreover, the limitation of thickness puts forward a request for a high retention rate of the coatings. In response to these challenges, this study presents an innovative approach aimed at enhancing the robustness of superhydrophobic nanocomposite coatings through the utilization of a straightforward dual spraying technique. The results demonstrate that the particles with hierarchical micro/nanostructures fabricated by the primary spraying process provide abundant roughness feedstocks for the secondary‐sprayed coatings, in which superhydrophobicity properties can be achieved with less NP content. Additionally, the mechanical durability of the coatings can be reinforced by the addition of appropriate amounts of aluminum oxide (Al2O3) NPs and the continuous‐distributed particles fabricated by the primary‐spraying process, exhibiting a longer abrasion distance and a higher retention rate. Also, the prepared sample shows comprehensive robustness in adhesion, abrasion, and dynamic impact tests. By offering insights into material selection and process optimization, this study paves the way for creating resilient superhydrophobic coatings using a streamlined and convenient approach.

Double-layer with electroactive and superhydrophobicity based on polymer nanotubes to improve robustness and anti-corrosion performances

The phenomena of corrosion in metals have resulted in significant damage to the day-to-day lives of humans, the routine maintenance of engineering metal materials, and catastrophic corrosion damage has also triggered huge economic losses. Herein, we propose a double-layer PDVB/FSiO2-PDVB@PPy/EP sprayable coating with excellent robust superhydrophobicity and electroactive based on mass-producible polydivinylbenzene nanotubes (PDVB NTs) to apply in anti-corrosion of Q235 steel plate. On one hand, the electroactive base layer of PDVB@PPy/EP can constitute a physical barrier against corrosive media; On the other hand, cross-linked PDVB NTs containing FSiO2 NPs (PDVB/FSiO2 NTs) can form a superhydrophobic surface structure to avoid substrate corrosion from corrosive liquid. The water contact angle (WCA) of the composite coating is 163.9° and the sliding angle (SA) is 3.6°, indicating that the coating possesses excellent superhydrophobic properties. Remarkably, Cross-cut scratch, tape peel, and Taber abrasion tests confirm that the composite coating exhibits excellent robust performance. The pitting pit depth after 30 days of salt spray test is 4 μm, and following 60 days of immersion in a solution containing 3.5 wt% NaCl, the protection efficiency (P.E.%) reaches 94.79 %. These results suggest that the double-layer electroactive superhydrophobic coating exhibits excellent corrosion resistance.

An experimental study on high strength self-compacting concrete inclusion of zeolite and silica fume as a potential alternative sustainable cementitious materials

One of the major sources of carbon dioxide and other greenhouse gases around the world is the cement industry. They make up 6–8 % of global warming. Therefore, by conducting this experiment, we may examine the possibility of replacing cement with different cementitious materials which include zeolite,silica fume and fly ash. These mineral additives will lessen the need for cement while enhancing the properties of the concrete that has just been hardened and also in fresh state. The objective of this experiment is to explore the impact of zeolite and silica fume on the physical and durability qualitiesof high strength, self-compacting concrete utilising nano silica that has been optimised. In the course of this study, various concrete mixtures were cast with zeolite and silica fume substituted for cement in varying amounts, and there was also a control mix for reference. These additives arereplacedcement in multiples of 5 up to 20 %. The preferred dosage as 2 % Nano silica is substituted as a regular mineral additive in all mixtures. Workability tests on the fresh qualities of concrete mixtures are conducted and the EFNARC stipulations are met by these experimental findings. All the concrete mixes' parameters, including strengths like splitting tensile and compressive were identified. Tests such as the Rapid chloride permeability test, the abrasion test, water absorption and desorption test were used to evaluate the concrete's durability.

Enhanced mesoscale and macroscale parameters for accurate 3D shape characterization

This paper investigates the limitations of widely used 3D Wadell's roundness and true sphericity metrics for characterizing granular materials. It introduces two improved indices: the mesoscale interlocking index and the radial distance factor. The study involves diverse particles scanned using optical interferometry and X-ray computed tomography. A mean curvature method is employed for surface segmentation, and a computationally efficient 3D mesh simplification procedure is proposed. Python scripts are developed for surface segmentation, mesh simplification, and 3D shape characterization. The new indices are validated by assessing angular and rounded 3D particles and changes in the shape of aggregates through the Los Angeles abrasion test. The results demonstrate the ability of the proposed indices to differentiate visually similar particles with identical Wadell's roundness and true sphericity, showcasing their effectiveness in accurately describing particle shape. The statistical distribution of 3D particle curvatures offers an alternative method for understanding particles' shape and abrasion.

Design of fluorine-free superhydrophobic coating for fibred architectonic concrete

In outdoor environment, the exterior walls surface of buildings always suffers from damages caused by ultraviolet radiations, temperature variation, abrasion and erosion phenomenon, dust pollution, and microbial adhesion: Thereby reducing their durability over time. In order to overcome these obstacles, the superhydrophobic coatings can be an advantageous solution to ensure long-term stable use by improving the exterior concrete walls durability. In this line, a fluorine-free water-repellent coating was developed through sol-gel method and successfully applied to concrete substrates by dip-coating technique. The coating was formulated with low surface energy polydimethylsiloxane (PDMS) and polymeric silica (PS) to simultaneously modify the microstructure and chemical properties of concrete substrate surface. The coated concrete substrate showed super-hydrophobicity with high water contact angle (WCA) over than 150°. Besides, the self-cleaning property, mechanical robustness, stability under UV irradiations, resistance to temperature and humidity were investigated. The results indicated that the coated concrete substrate cannot be soiled by dust and can resist over than 300 cycles of abrasion test. It also presents resistance to temperature of 45°C associated with a humidity of 80% during 720 hours and showed excellent resistance to prolonged exposure to UV irradiations during 1440 hours. Natural out-door aging tests have shown that the superhydrophobic coating is weather resistant.

A review of Enhancing Abrasion Resistance of Dry Geopolymer Ramie Fiber Composite Mortar in Hydraulic Structures

Hydraulic structures, such as dams, spillways, and tunnels, suffer from severe abrasion and erosion due to the continuous flow of water and particles carried away. Such damage will result in expensive operating and maintenance of hydraulic structures. The purpose of this review is to discuss various abrasion testing methods as well as various efforts enhancing abrasion resistance, such as adding silica fume, and fibers, improving quality, and using geopolymers. In conclusion, the development of dry geopolymer methods offers great potential for use because they are more practical than wet geopolymer systems, however, the brittle nature of geopolymers is a weak point, which can be addressed by adding composite materials, such as ramie fiber. With the expectation that the matrix of composite geopolymer mortar with ramie fiber will have good abrasion resistance. Further research and development are needed to address existing challenges and establish this innovative construction material as a viable solution for sustainable hydraulic applications.

Insights into metal wear and particle breakage using Bond's abrasiveness test

Nearly 80 years ago Fred Bond proposed his abrasiveness test, also known as Allis Chalmers abrasion test, together with empirical equations that have been used to predict the wear of mill and crusher liners, besides grinding media. Although those equations have been widely criticized over the years, in particular owing to the limited accuracy of the correlations originally proposed to predict wear, it remains the most widely used test to measure ore abrasiveness in the minerals industry. The work analyzes the test, through experiments conducted under conditions that differ from those originally proposed by Bond in order to gain insights on metal wear and particle breakage. The effects of particle size, ore competence, metal hardness and time of batch operation are analyzed. It is shown that initial particle size strongly affects the rate of wear, that the intensity of fragmentation varies with hardness of the paddle and that the size distribution from the ground material offers a valid proxy for ore competence that may be useful in geometallurgical studies.

Development of polylactic acid‐untreated bamboo filler composite and its chemical and mechanical properties

AbstractA fully bio‐based plastic composite comprising a polylactic acid (PLA) matrix with untreated bamboo filler (BF) was manufactured by a simple method. PLA and crushed bamboo flakes were compounded in a kneader and then injection molded without pretreatment of BF. The composites containing PLA and BF at 50:50 (PLA50/BF50) and 60:40 mass ratios (PLA60/BF40) were obtained. The PLA60/BF40 and PLA50/BF50 products were evaluated by thermal analysis (TG/DTA, DSC, and DMA), Fourier transform infrared (FTIR) spectroscopy analysis, and abrasive wear test. From the results, the composite of PLA and untreated BF was fabricated under high temperature and high‐pressure conditions, in kneading at 180°C and injection molding at 150–175°C and 95 MPa for 1.5 s. FTIR analysis indicated that changes in the functional groups of the composite products were dependent on the proportion of BF. Unfortunately, the BF did not improve the stiffness, viscoelasticity, and wear resistance of the PLA. However, the PLA50/BF50 product had a storage modulus comparable to that of the pure PLA product, and of which a 30% cost reduction was achieved by using abundant bamboo and reducing the amount of PLA.

Performance Study of Sustainable Concrete Containing Recycled Aggregates from Non-Selected Construction and Demolition Waste

In the present study, we investigated the mechanical performance of concrete composed of non-selected construction and demolition waste (C&DW) sourced from both old and new sections of an inactive waste landfill site in Karaj, Iran. Initially, we determined the composition of the coarse and fine C&DW used in concrete production. Subsequently, we meticulously examined the physical and chemical properties of both the C&DW and virgin materials to enable thorough comparisons of the results. We then conducted experimental analyses on 33 concrete mixtures containing recycled C&DW, utilizing various tests, including a compressive strength test (CST) for cylindrical and cubic samples, modulus of elasticity (MOE), wide wheel abrasion test (Capon test), British pendulum number (BPN), and ultrasonic pulse velocity (UPV) test. We considered both non-separated fine and coarse C&DW at different replacement ratios in the recycled concrete (RC). Our findings indicate that using non-separated coarse and fine C&DW in concrete yielded satisfactory results, leading to significant savings in virgin materials required for concrete preparation and promoting sustainable development. Furthermore, non-selected C&DW proved to be a viable sustainable material for similar concrete applications. The results revealed a decrease in brick material consumption in various constructions over the past 20 years in Karaj, contributing to the enhanced strength of C&DW concrete. However, the presence of clay minerals in aged landfill sites can adversely affect concrete performance as a potential destructive factor. Despite the possible negative impact of incorporating fine recycled C&DW materials on concrete mechanical performance, the Capon test results demonstrated that the presence of coarse C&DW can enhance concrete’s wear resistance.

Superhydrophobic Surfaces with Excellent Ice Prevention and Drag Reduction Properties Inspired by Iridaceae Leaf.

The anti-icing and drag-reduction properties of diverse microstructured surfaces have undergone extensive study over the past decade. Nonetheless, tough environments enforce stringent demands on the composite characteristics of superhydrophobic surfaces (SHS). In this study, fresh composite structures were fabricated on a metal substrate by nanosecond laser machining technology, drawing inspiration from the hardy plant Iridaceae. The prepared sample surface mainly consists of a periodic microrhombus array and irregular nanosheets. To comprehensively investigate the effect of its special structure on surface properties, three surfaces with different sizes of rhombic structures were used for comparative analysis, and the results show that the SH-S2 sample is optimal. This can significantly delay the freezing time by an impressive 1404 s at -10 °C while revealing the sample surface anti-icing strategy. In addition, the rheological experiments determined over 300 μm of slip length for the SH-S2 sample, and the drag reduction rate of the surface reaches nearly 40%, which is well aligned with the results of the delayed icing experiments. Finally, the mechanical durability of the SH-S2 surface was investigated through scratch damage, sandpaper abrasion, reparability trials, and icing and melting cycle tests. This research presents a new approach and methodology for the application of SHS on polar ship surfaces.

Effects of niobium and molybdenum addition on microstructural characteristics and wear properties of 14 wt%Cr white cast irons

White cast iron (WCIs) alloys were developed by adding Nb, Mo, and a combination of both (∼3 wt% Nb, ∼3 wt% Mo, ∼1 wt% Mo-2 wt% Nb) through melting and casting. The objective was to analyze the microstructural characteristics of the alloys, as well as the impact of reinforcing carbides on their mechanical and tribological properties. The alloy containing the highest percentage of niobium exhibited a refined microstructure, tending towards a eutectic structure, unlike the Mo-containing materials with totally hypoeutectic microstructures. The microstructural characteristics of the alloys and morphology of niobium carbides, as well as the percentage of M7C3 eutectic carbides produced were affected by the varying percentages of Nb and the Mo–Nb combination. Moreover, thermodynamic simulations revealed that the NbC carbide precipitated before the M7C3 eutectic carbides, austenite dendrites, and the MC (composed mainly of Nb containing bound Mo) carbide resulting from the Mo–Nb combination. The alloys containing Mo had similar bulk hardness values, while the alloy with the highest percentage of Nb showed a higher bulk hardness value. This was attributed to the effect of Nb on microstructure refinement and on the production of M7C3 eutectic carbides from the alloy. Although there were different reinforcing carbides (NbC, MC and M2C), the differences in microstructural characteristics had no noticeable influence on the Charpy impact energy. Micro-scale abrasive wear test (conducted with SiC abrasive slurry) demonstrated that the reinforcing carbides MC and mainly NbC had a beneficial effect in blocking and preventing the progression of continuous micro-cuttings and formation of grooves. The M7C3 and M2C carbides were less effective at protecting the matrix against the high-hardness SiC abrasive.

Towards transparent and durable copper-containing antimicrobial surfaces

Metallic copper is a potent antimicrobial agent with high efficacy against a range of microorganisms. Whilst it is commonplace for objects such as door handles and hospital bedrails to be made of or to be coated with copper, other high-touch surfaces such as those of screens and monitors would lose their optical transparency. Herein, we report the design of a transparent antimicrobial nanostructured copper surface obtained by dewetting ultrathin metal copper films on glass. Antimicrobial effectiveness of >99.9 % was obtained within 2 h against Staphylococcus aureus following the US Environmental Protection Agency Test method. Moreover, the proposed surfaces show an average transmittance between 70–80% with little color in the visible range. Additionally, they maintain optical and antimicrobial properties after abrasion and chemical exposure tests designed to replicate physical wear and repeated exposure to biocidal cleaning materials. With the demonstrated surfaces’ antimicrobial, colorless, and durability properties, they have potential in applications such as touch-enabled public or personal displays once higher transparency is achieved.

A New Composite Material with Energy Storage, Electro/Photo-Thermal and Robust Super-Hydrophobic Properties for High-Efficiency Anti-Icing/De-Icing.

All weather, high-efficiency, energy-saving anti-icing/de-icing materials are of great importance for solving the problem of ice accumulation on outdoor equipment surfaces. In this study, a composite material with energy storage, active electro-/photo-thermal de-icing and passive super-hydrophobic anti-icing properties is proposed. Fluorinated epoxy resin and MWCNTs/PTFE particles are used to prepare the top multifunctional anti-icing/de-icing layer, which exhibited super-hydrophobicity with water contact angle greater than 155° and conductivity higher than 69Sm-1. The super-hydrophobic durability of the top layer is verified through tape peeling and sandpaper abrasion tests. The surface can be heated by applying on voltage or light illumination, showing efficient electro-/photo-thermal and all-day anti-icing/de-icing performance. The oleogel material at the bottom layer is capable to absorb energy during heating process and release it during cooling process by phase transition, which greatly delayed the freezing time and saved energy. The icing test of single ice droplet, electro-/photo-thermal de-icing and defrosting tests also proved the high efficiency and energy saving of the anti-icing/de-icing strategy. This study provided a new way to manufacture multi-functional materials for practical anti-icing/de-icing applications.

Color and surface roughness alterations of bulk-fill resin composites submitted to simulated toothbrushing with whitening dentifrices

Aim: To evaluate the surface roughness and color stability of bulk-fill resin composites after simulated toothbrushing with whitening dentifrices. The radioactive/relative dentin abrasion (RDA) and radioactive/relative enamel abrasion (REA) of dentifrices were also assessed. Methods: Specimens (n=10) of Tetric N Ceram Bulk Fill (TNCB), Filtek One Bulk Fill (FOB) resin composites, and Z100(Control) were prepared using a cylindrical Teflon matrix. Surface roughness (Ra, μm) was assessed by a roughness meter and the color evaluations (ΔEab , ΔE00 , WID ) were performed using a digital spectrophotometer based on the CIELAB system. Three measurements were performed per sample, before and after simulated toothbrushing with 3D Oral-B White Perfection (3DW) and Black is White (BW) dentifrices. The abrasivity (REA and RDA values) of the used dentifrices was also determined by the Hefferren abrasivity test. Results: The Ra values increased significantly in all resin composites after 3DW and BW toothbrushing. The acceptable threshold color varied among resin composites, and TNCB and Z100 presented the highest ΔEab and ΔE00 for BW dentifrice. The 3DW dentifrice was significantly more abrasive than BW dentifrice on enamel and dentin. Conclusions: simulated toothbrushing with tested whitening dentifrices increased the surface roughness at acceptable levels. The Tetric N Ceram Bulk-fill and Z100 composite showed the highest color alteration in BW. 3D White Perfection dentifrice was more abrasive on dentin and enamel than Black is White.

High mechanical strength superhydrophobic colored sand prepared by a low-temperature strategy

The desert aeolian sand is one of the most abundant resources worldwide, and the utilization of sand with superhydrophobic function has become a heated research field. However, same as other superhydrophobic materials, the abrasion of the surface will lead to the loss of hydrophobic performance. Therefore, we prepared high-performance and mechanically stable superhydrophobic colored sand with a maximum water contact angle of 155° by low-temperature layered chaining technique (80 °C). The technical property of the co-existence of superhydrophobicity and mechanical stability was achieved on the surface of our high mechanical strength superhydrophobic colored sand. The interaction between the grafted particles and water molecules was revealed by molecular adsorption dynamics simulation to investigate the factors that affect hydrophobicity performance. The prepared superhydrophobic colored sand presented stable superhydrophobic performance after 40 min continuous abrasion tests. Moreover, the superhydrophobic sand had excellent chemical stability and liquid impact resistance with the composition stability under 240 °C. This work presents an environment-friendly, and resource-utilization surface modification method on inert materials like sand under a low-temperature condition. It provides framework surfaces like road ground and architectures with high mechanical strength and functional “layer” through a long-term performance and stable method.