Scratch Hardness Test Research Articles

Scratch resistance and in-vitro biocompatibility of plasma-sprayed baghdadite coatings reinforced with carbon nanotubes

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) coatings, commonly used for metallic implants, have limitations such as excessive brittleness, low fracture toughness, inadequate wear resistance, and slow osseointegration properties. In contrast, baghdadite (BAG, Ca3ZrSi2O9), a calcium zirconium silicate-based bioceramic, exhibits outstanding biological properties, to promote cell proliferation and differentiation of human osteoblasts along with adequate mechanical strength. In this study, plasma-sprayed HA, BAG, and carbon nanotubes (CNT, 1 wt%, and 2 wt%) reinforced BAG coatings are deposited on titanium (Ti) substrate to enhance its mechanical as well as biological properties. The microhardness values of CNT-reinforced BAG coatings increase due to a decrease in porosity and the retention of CNT inside the BAG matrix. Progressive loading scratch tests are performed, revealing a reduction in wear volume loss from 15.051 mm3 to 12.574 mm3 and scratch rate from 43.262 mm3N−1 m−1 to 36.172 mm3N−1 m−1 with the addition of 2 wt% CNT in BAG coatings. The scratch hardness test results demonstrated that introducing CNT into BAG coating significantly enhances its performance, showing a remarkable 38.7 % improvement. In-vitro cell culture studies indicate excellent cell adhesion, growth, and proliferation of MC3T3-E1 osteoblast cells on the surfaces of the CNT-reinforced BAG coatings.

Evaluation of mechanical and tribological behavior of galvanized, galvalume and polyurethane-coated steel sheets

The current study is performed on three coated steel sheets to evaluate their mechanical and tribological properties. The optical micrograph reveals the dark pearlite structure in the ferrite matrix, whereas the grain size analysis reveals the 4.07 μm mean grain size of the ferrite. The scratch hardness test reveals better scratch-resistant properties for all three experimental samples. The Nanoscratch test reveals a decrease in friction with increasing load from 50 mN to 150 mN for the colour-coated samples. The tensile study shows higher YS and UTS values (410 MPa and 450 MPa, respectively) for the galvalume sample, followed by galvanized and colour-coated steel. In contrast, a higher ductility (~33%) is observed for the colour-coated sample, followed by galvanized and galvalume samples. It is evident and appropriate from the dry heat resistance test that all three steel sheets, viz. galvalume, galvanised and colour coated sheet, can withstand 120 °C of heat for 24 h. So, all the samples show improved heat resistance properties. Taber abrasion resistance test results reveal that the colour-coated sample shows improved abrasion resistance due to the polyurethane coating followed by galvalume and galvanized steel samples.

Investigation of Various Coating Resins for Optimal Anticorrosion and Mechanical Properties of Mild Steel Surface in NaCl Solution

The primary objective of the research was to investigate the ideal resin coating on the mild steel surface among various resin coatings which are in use. These resin coatings are used as an anti-corrosive material for mild steel surfaces with enhanced mechanical properties. The resins (epoxy, polyurethane, polyester, and phenolic) on mild steel surface were applied by the pneumatic spray coating method. In addition, immersion test and salt spray test methods were followed using sodium chloride (NaCl) solution. Furthermore, the rate of corrosion and mechanical properties of mild steel coated with different resins was evaluated by conducting various experiments (immersion test, salt spray test, tensile strength test, and scratch hardness test) and was compared with a bare mild steel surface. The results of the current research showed that the mild steel surface coated with epoxy resin was found to be the most effective corrosion resistance material with better mechanical properties compared to other tested mild steel resin-coated surfaces.

Development and property evaluation of alkyd resins from watermelon (Citrullus lanatus) seed oil

Watermelon Seed Oil (WSO) has been investigated for its suitability in the development of alkyds. Chemical method is used to extract the oil, and the WSO's physicochemical properties are determined. The alcoholysis-esterification method is used to prepare two grades of alkyds containing 30 percent WSO (alkyd I) and 60 percent WSO(alkyd II).The progress of the reaction is monitored by determining the volume of water of condensation and acid value as the reaction progresses. Film properties of the prepared alkyd are determined. The results of the physicochemical properties of the WSO reveal an iodine value of 119.38 gI2/100g indicating that it is semi-drying oil and can serve as a modifier for alkyd resins production for the paint industry. Alkyd I has a higher acid value, a greater degree of polymerization and extent of the polymerization than alkyd II, according to the results. Alkyd II produce a harder film than that of alkyd I as observed from the scratch hardness test. Also, both alkyd show good flexibility properties and have good impact resistance on the coated panel. The present study, therefore, suggests that WSO can be considered as a modifier for alkyd resins production for the paint industry.

A force model for face grinding using digital graphic scanning (DGS) method

The prediction of grinding force has great significance in improving grinding quality and efficiency. This paper presents a predictive force model in plunge facing grinding considering both the cutting mechanism of single grain and the random nature of wheel topography. The model includes cutting deformation force and frictional force, which mainly depend on undeformed chip cross-section area and wear flat area of grains. In order to overcome the difficulties for calculating the cross-section area of irregular polyhedral grains, a digital graphic scanning (DGS) method is proposed in this research. Single grain scratch test and hardness test are carried out to obtain the model coefficients. The validation experiments performed on a face grinding machine show a good match of the predictive and measured forces for different grinding parameters.

Characterization of Surface Coating Techniques for Improved Performance

Surface coating has evolved with time, tracking the demands of the processing industry. This research activity, studies the significance of powder coatings in the evolution of existing conventional surface coating technology for their practical applications in the field of metal coating, particularly office and home appliances. The first objective of this work involves a systematic comparison between polymer powder coatings with liquid-based coatings. In the second objective, a comparison between the polymer coatings with additive filled powder coating was performed. Various conventional substrates (such as copper, aluminium, galvanized iron, brass, cement plank, wood block) were used for this study. The materials were first dry scuffed and then dipped in 3 in 1 chemical (zinc phosphate chemical and magnesium phosphate) for the primer coat. The prepared substrates were surface coated with liquid paint (on one side of the panel) using spray gun and powder paint (on another side of panel) using electrostatic spraying. The coated panels are then subjected to various standard (ISO) characterization techniques such as Scratch hardness test, Flexibility test, Thickness test, Adhesion test, Impact resistance test etc to analyze the effectiveness of the coatings applied. The quantitative and qualitative results thus obtained using powder coatings were promising (e.g: As the load progressively kept increasing i.e. 1000-2000 gm, mild scratches were noticeable on liquid coated substrates whereas powder coated metal panels have shown a greater resistance to scratch damage) as the test values determined high strength quality and durability (in-line with the standards) in comparison with liquid coatings. Also, the doping of additive (graphene) in small quantity has improved characteristics and qualities of the powder coated materials (e.g: graphene based powder coating has endured scratch hardness test beyond 2500 gms load force compared to simple powder coating). The findings of the current research study has confirmed the advantage of the powder coating technology and also deliberated the effect of fine powder flow ability. The important future prospects of this research work is that., powder coatings will stand on the threshold of exciting breakthroughs thus opening new frontiers by being able to coat thick steel components and even non-metal substrates. Also, the recent advances in powder coating technology with anticorrosive additives will result in bonded metallic coatings that deliver a unique, quality appearance.

Composites of titanium nano and micro-particles and UHMWPE for enhanced performance properties

A series of composites of UHMWPE filled with various amounts of Titanium (Ti) particles in micron and nano-sizes was developed to explore the possibility of enhancing wear performance. Mechanical properties such as tensile strength, impact strength, Young’s modulus and % elongation showed significant improvement with an increase in Ti particles up to certain amount followed by a decline. Tribological properties were evaluated in a single-pass abrasive wear mode using a pin on disc configuration. The wear resistance of UHMWPE showed significant improvement up to a certain amount of particles. The coefficient of friction also reduced drastically. Vickers and Scratch hardness tests were carried out using diamond indenter. X-ray tomography was done to analyze the dispersion of particles in the matrix. Wettability studies and worn surface analysis were done on the composite- surfaces. Incorporation of Ti particles improved the strength of the composites significantly. The composites showed low wear rates (≈10−10 m3 Nm−1) and were correlated with scratch hardness. Various wear mechanisms like micro-cutting, micro-ploughing and groove-formation were also observed in Scanning electron micrographs (SEM). Nano-particles outperformed micro-particles in almost all properties.

Influence of Selective Laser Melting Technological Parameters on the Mechanical Properties of Additively Manufactured Elements Using 316L Austenitic Steel.

The main aim of this study was to investigate the influence of different energy density values used for the additively manufactured elements using selective laser melting (SLM).The group of process parameters considered was selected from the first-stage parameters identified in preliminary research. Samples manufactured using three different sets of parameter values were subjected to static tensile and compression tests. The samples were also subjected to dynamic Split–Hopkinson tests. To verify the microstructural changes after the dynamic tests, microstructural analyses were conducted. Additionally, the element deformation during the tensile tests was analyzed using digital image correlation (DIC). To analyze the influence of the selected parameters and verify the layered structure of the manufactured elements, sclerometer scratch hardness tests were carried out on each sample. Based on the research results, it was possible to observe the porosity growth mechanism and its influence on the material strength (including static and dynamic tests). Parameters modifications that caused 20% lower energy density, as well as elongation of the elements during tensile testing, decreased twice, which was strictly connected with porosity growth. An increase of energy density, by almost three times, caused a significant reduction of force fluctuations differences between both tested surfaces (parallel and perpendicular to the building platform) during sclerometer hardness testing. That kind of phenomenon had been taken into account in the microstructure investigations before and after dynamic testing, where it had been spotted as a positive impact on material deformations based on fused material formation after SLM processing.

Surface Properties of Structure-Controlled Silica Films Prepared Using Organic-Inorganic Hybrid Solutions

Silica films with various microstructures were fabricated using organic-inorganic (O-I) hybrid solutions containing a mixture of silica sols, polymethylmethacrylate (PMMA), and urethane acrylate nonionomer (UAN) as an amphiphilic polymer, The O-I hybrid solutions were prepared with various UAN:PMMA and polymer/solvent ratios, then spin-coated on glass and calcinated at 450 °C to produce silica films with various microphase-separated structures. For higher UAN and PMMA concentrations, the silica films showed spherical inorganic domains dispersed over the surface, while many pores were formed in the films with lower polymer contents (observed using scanning electron microscopy). The surface hydrophobicity of the silica films was determined using water contact angle measurements. After surface modification using (1H, 1H, 2H, 2H-perfluorooctyl)trichlorosilane solution, the hydrophobicity of films with a highly microphase-separated structure increased significantly, and all surface-modified films showed increasing hydrophobicity with increasing polymer content. Furthermore, pencil scratch hardness tests showed that the silica films formed on glass substrates could withstand the 5H scratch, test even after surface modification.

Corn oil based poly(urethane-ether-amide)/fumed silica nanocomposite coatings for anticorrosion application

Poly(urethane-ether-amide) (PUIEtA) nanocomposite coatings on mild steel were prepared by using corn oil, isosorbide and isophorone diisocynate and fumed silica. The syntheses steps were confirmed by FTIR, 1H NMR and 13C NMR spectroscopy techniques. The morphology of PUIEtA nanocomposite coating was studied by SEM-EDX, that confirmed the presence of nanosilica and thermal behavior was studied by DSC/TGA analysis. The anticorrosion performance of PUIEtA coating systems on mild steel, exposed to 3.5 wt% NaCl solution, was evaluated using electrochemical impedance spectroscopy. Scratch hardness, pencil hardness, adhesion, and bending test were performed in order to investigate the performance of nanocomposite coating on mild steel substrate. It was found that PUIEtA-fumed silica nanocomposite coating could provide much better protection than PUIEtA. PUIEtA-3 nanocomposite coating can be safely used up to 200 °C.

Characterization of DC Magnetron Sputtered Copper Thin Film on Aluminium Touch Surface

Hospital care-assisted infections introduce problems like prolonged hospital stay, additional financial burden and higher death rate. Since copper is registered by US Environmental Protection Agency as the only solid antimicrobial metal, it could be used in hospital touch surfaces. In the present work, copper has been deposited on the aluminium substrate by DC magnetron sputtering method with different target power. Prior to the coating, the substrate has undergone double zincation process. The coating has been characterized by XRD, SEM, TEM, scratch hardness test and microhardness test. From the TEM micrographs, the grain size has been found to decrease from 49 to 18 nm on increasing the deposition power from 50 to 150 W. Along with the decrease in the grain size, the mechanical properties like scratch hardness and microhardness of the coating have been increased. The preferred growth along [111] direction observed in XRD analysis is responsible for the increase in the hardness of the coating apart from the presence of the nano-grains. The SEM image of the coating shows nodular morphology which enhances the surface area.

Experience in Detonation Nano-Structures Coating Application Technologies using Condensed Explosives and Gas Mixtures

Objectives: The article gives an insight to reviews and research in detonation nano-structured coating, using condensed explosives and gas mixtures applied at the SamSTU and other facilities in the Samara region. Methods: The detonation method allows obtaining nanostructured composite materials and coatings that are unique in their physical and mechanical properties. Detonation sputtering is a coating technology that relies on gas explosion energy for heating and accelerating a powdered material. Findings: The experience of industrial use of wear-resistant detonation coatings and possible applications has been demonstrated. According to our research, it is possible to raise surface hardness of specimens by more than 3 times and 2 to 10 times with wear resistance. It is shown that the suggested technology ensures higher stability of mechanical properties of coatings. Thus, original hardness of steel specimens was in the range of 400 to 600 kgf/mm 2 . Hardness values of detonation-sputtered hard-alloy coatings were ca. 1,200 to 1,400 kgf/mm 2 and activation energy was up to 350 kJ/mole, which is typical of hard-alloy materials. Scratch-hardness tests showed rather high coating and base material adhesion values. According to the preliminary data, shear strengths over 150 MPa may be achieved. Thus, aluminum-substrate Al 2 O 3 strength was 163 MPa and aluminum-substrate and Ti-subcoat Al 2 O 3 strength was 152 MPa. Novelty/improvements: The suggested novel method enables to increase projection velocity of powdered materials and creates an extra heat effect giving plastic properties to the injected materials.

Scratch and wear resistance of nano-silica-modified silicate conversion coating on aluminium

The silicate conversion coating was modified with nano-silica and applied on the surface of AA2024 by dip-coating technique. The mechanical properties of produced modified silicate layer were investigated by the pencil scratch hardness, cross-cut and abrasion resistance tests. The characterisation of coated surface before and after the tests was studied with optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy and atomic force microscopy. Addition of nano-silica to the silicate coating caused an enhancement in the SiO2:K2O ratio. The results showed that the homogeneity of coating surfaces increased in the presence of nano-silica. The wear and scratch resistance of the modified silicate layer improved against the sliding conditions. In addition, the adhesion of coating layer to the substrate metal increased.

Color tunable low cost transparent heat reflector using copper and titanium oxide for energy saving application.

Multilayer coating structure comprising a copper (Cu) layer sandwiched between titanium dioxide (TiO2) were demonstrated as a transparent heat reflecting (THR) coating on glass for energy-saving window application. The main highlight is the utilization of Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass. Color tunable transparent heat reflecting coating was realized through the design of multilayer structure and process optimization. The impact of thermal treatment on the overall performance of sputter deposited TiO2/Cu/TiO2 multilayer thin film on glass substrate is investigated in detail. Significant enhancement of transmittance in the visible range and reflectance in the infra-red (IR) region has been observed after thermal treatment of TiO2/Cu/TiO2 multilayer thin film at 500 °C due to the improvement of crystal quality of TiO2. Highest visible transmittance of 90% and IR reflectance of 85% at a wavelength of 1200 nm are demonstrated for the TiO2/Cu/TiO2 multilayer thin film after annealing at 500 °C. Performance of TiO2/Cu/TiO2 heat reflector coating decreases after thermal treatment at 600 °C. The wear performance of the TiO2/Cu/TiO2 multilayer structure has been evaluated through scratch hardness test. The present work shows promising characteristics of Cu-based THR coating for energy-saving building industry.

Defining the Brittle Failure Envelopes of Individual Reaction Zones Observed in CO2-Exposed Wellbore Cement.

To predict the behavior of the cement sheath after CO2 injection and the potential for leakage pathways, it is key to understand how the mechanical properties of the cement evolves with CO2 exposure time. We performed scratch-hardness tests on hardened samples of class G cement before and after CO2 exposure. The cement was exposed to CO2-rich fluid for one to six months at 65 °C and 8 MPa Ptotal. Detailed SEM-EDX analyses showed reaction zones similar to those previously reported in the literature: (1) an outer-reacted, porous silica-rich zone; (2) a dense, carbonated zone; and (3) a more porous, Ca-depleted inner zone. The quantitative mechanical data (brittle compressive strength and friction coefficient) obtained for each of the zones suggest that the heterogeneity of reacted cement leads to a wide range of brittle strength values in any of the reaction zones, with only a rough dependence on exposure time. However, the data can be used to guide numerical modeling efforts needed to assess the impact of reaction-induced mechanical failure of wellbore cement by coupling sensitivity analysis and mechanical predictions.

Methyltrimethoxysilane을 이용한 반사방지 코팅막의 성능 향상

Traditional anti-reflective (AR) coating films prepared using tetraethylorthosilicate (TEOS) as a precursor absorbs water easily in addition to having a weak abrasion resistance. To improve the transmittance, hydrophobicity and abrasion resistance of AR coating film, various AR coating films were prepared using methyltrimethoxysilane (MTMS) as a precursor in addition to in- troducing a fluoroalkylsilane, acid catalyst, base catalyst and acid-base two step catalyst. The prepared AR coating films were then characterized by UV-Vis spectroscopy, contact angle analyzer, atomic force microscope (AFM), pencil scratch hardness test and cross-cut test. As a result, the transmittance of bare glass was 90.5%, while that of AR coating glass increased to 94.8% at curing temperature of 300 ℃. When the fluoroalkylsilane was added, the water contact angle of AR coating film increased from 96.3° to 108°, indicating that the hydrophobicity of the film was greatly improved. The abrasion resistance of AR coating film was also improved by the acid catalyst, whereas the transmittance increased by the base catalyst. In the case of AR coating film prepared using an acid-base two step catalyzed reaction, both the transmittance and abrasion resistance of the film was synergistically enhanced as compared with those of AR coating films prepared without introduction of a catalyst.

Electrodeposition of an aluminum coating on a graphite surface from a molten AlCl3–NaCl–KCl mixture

An electrochemical method was used to deposit aluminum on a graphite plate in a molten NaCl–KCl–AlCl3 mixture with a weight ratio of 1:1:8 to form a coatings with different thicknesses. The thickness and morphology of the coating were controlled by the current density and electrochemical deposition time. Results indicated that the thickness of the coating increased with deposition time up to 240 min at a current density of 1.06 A/dm2 and a dendritic structure coating was formed by increasing the deposition time beyond 300 min. The greater the current density, the faster the deposition rate. When the current density was increased to 3.28 A/dm2, the thickness of the coating reached a maximum of 148 μ m for an electrochemical deposition time of 120 min. Excellent adhesion strength between the aluminum coating and graphite substrate was proved by thermal shock resistance and scratch hardness tests. The thermal conductivity of the samples was increased significantly from an initial value of 115.7–199.0 W/(m K). [New Carbon Materials 2015, 30(3): 282–288]

Development of Titanium Dioxide (TiO2 ) Nanocoatings on Food Contact Surfaces and Method to Evaluate Their Durability and Photocatalytic Bactericidal Property.

Titanium dioxide (TiO2 ) is a well-known photocatalyst for its excellent bactericidal property under UVA light. The purpose of this study was to develop physically stable TiO2 coatings on food contact surfaces using different binding agents and develop methods to evaluate their durability and microbicidal property. Several types of organic and inorganic binders such as polyvinyl alcohol, polyethylene glycol, polyurethane, polycrylic, sodium and potassium silicates, shellac resin, and other commercial binders were used at 1:1 to 1:16 nanoparticle to binder weight ratios to develop a formulation for TiO2 coating on stainless steel surfaces. Among the tested binders, polyurethane, polycrylic, and shellac resin were found to be physically more stable when used in TiO2 coating at 1:4 to 1:16 weight ratio. The physical stability of TiO2 coatings was determined using adhesion strength and scratch hardness tests by following standard ASTM procedures. Further, wear resistance of the coatings was evaluated based on a simulated cleaning procedure used in food processing environments. TiO2 coating with polyurethane at a 1:8 nanoparticle to binder weight ratio showed the highest scratch hardness (1.08 GPa) followed by coating with polycrylic (0.68 GPa) and shellac (0.14 GPa) binders. Three different techniques, namely direct spreading, glass cover-slip, and indented coupon were compared to determine the photocatalytic bactericidal property of TiO2 coatings against Escherichia coli 0157:H7 at 2 mW/cm(2) UVA light intensity. Under the tested conditions, the indented coupon technique was found to be the most appropriate method to determine the bactericidal property of TiO2 coatings and showed a reduction of 3.5 log CFU/cm(2) in 2 h.

태양전지 효율 향상용 졸-겔 법에 의한 반사방지 코팅막의 제조

2 Spawn Korea, 1337 Gwanpyeong-dong Yuseong-gu Daejeon, 305-509, Korea Abstract >> This study investigates the preparation of anti-reflective (AR) coating film to improve the efficiency of solar cell. The AR coating film was successfully obtained by dip-coating with AR coatings prepared by sol-gel method. Fluoroalkylsilane was additionally introduced into the coatings to give the self-cleaning effect of AR coating film. We performed the abrasion test, pencil scratch hardness test and cross-cut test to identify the mechanical strength of AR coating film. As the results, the transmittance of AR coating films with 9.07, 18.13 and 27.20 of IPA/MTMS molar ratios were 93.1, 93.6 and 95.3%, respectively. The water contact angle and transmittance of AR coating film increased by the introduction of hydrophobicity. The prepared AR coating film shows the high level of abrasion, hardness and adhesion. The IPA/MTMS molar ratio of 27.20 and the withdrawing speed range of 0.20 ~ 0.28cm/sec are the optimal coating condition in terms of the transmittance and mechanical strength of AR coating film.

Scratch Hardness of Polypropylenes: Effect of Applied Normal Force

A set of model polypropylene (PP) and talc-filled PP with various lubricants were prepared to study the effects of normal force on the scratch hardness of polymers. The effects of additives and annealing treatment on the scratch behavior of neat and talc-filled PP systems were investigated using a multiple-finger scratch test with focus on the influence of applied normal force on the scratch hardness. A way to revise the scratch hardness test method based on ASTM G171-03 (standard test method for scratch hardness of materials using a diamond stylus; ASTM International; West Conshohocken, PA) and ASTM D7027-05 (standard test method for evaluation of scratch resistance of polymeric coatings and plastics using an instrumented scratch machine; ASTM International; West Conshohocken, PA) is given. Differential scanning calorimetry and optical microscopy were used to characterize crystallinity, morphology, and scratch deformation mechanisms in the PP systems. It was found that the scratch hardness is related to the applied normal loads, the friction coefficient, and the fracture features generated during the scratch process. The talc-filled impact copolymer polypropylene (ICPP) exhibited higher scratch hardness than the neat ICPP. Homo-PP exhibited superior scratch resistance and less susceptibility to scratch deformation than ICPP. The addition of lubricant and annealing treatment improved the scratch resistance of both neat and the talc-filled PP systems.