Surface Scratch Resistance Research Articles

Effects of Microwave Treatment on Alkyd-Varnished Wood Exposed to Outdoor Conditions

In this study, it was planned to investigate the effects of microwave irradiation (MW) prior to varnish applications on the pine wood samples, which are subjected to three months of outdoor exposure. The samples of 180W15s, 270W15s, 360W5s, and 360W15s showed lower water sorption properties than the control, while the rest of the samples showed higher sorption properties than the control sample. The lowest water sorption value was 12.50% (-3.85% lower than the control). It was found that post-microwave treated samples provide a 1–3 degree increases in resistance against selected cold liquids of distilled water, fruit juice, milk and coke under similar conditions. After three months of outdoor exposure of the samples, the surface scratch resistance of the samples was found to be 1 to 4 degrees softer than the control sample (HB to 3B pencil hardness properties). However, the cross-cut properties of the samples showed almost similar level of adhesion properties, mostly between 2 and 3 (control sample: 3), which was assumed to be not notable different from control, regardless of treatment conditions. It was found to have various discoloration properties of the samples which subjected to weathering procedure of post-microwave treated and alkyd-varnish aplied samples. But the larger-sized samples (A-type) have a higher and wider range for b* (yellowness) and a* (redness) values, while smaller-sized samples (a-type) showed a wider range and higher brightness (L*) properties. Moreover, A-type samples had higher total color difference values than a-types at similar treatment conditions. It is important to note that all measured samples show an ΔE >1.0 (metric) value, which means the discoloration after three months of outdoor exposure could be realizable when carefully examined by the human eye. The results clearly indicated that the post-microwave radiation before alkyd-varnish application on pine wood samples were some level influences regarding the selected properties. The resistance of selected household cold liquids and surface cross-cut properties were prominent for some samples. In spite of wide properties measured, no any clear trend was found between MW radiation and selected properties.

The Impact Of Ultrasound-Assisted Mixing Method For Varnish And Components On The Varnish Layer’s Surface Hardness And Surface Scratch Resistance

The objective of this study was to determine effects of mechanical and ultrasound-assisted stirring methods for varnish + components mixing on the varnish layer’s surface hardness and surface scratch resistance. The study focused on polyurethane, acrylic, and polyester varnish systems, which were applied to three distinct wood types: Scots pine (Pinus sylvestris L.), Turkish beech (Fagus orientalis Lipsky), and African mahogany (Khaya ivorensis A. Chev.). The mixing processes included mechanical stirring for 3 and 5 minutes, as well as ultrasound-assisted stirring with varying power levels (80 watts and 120 watts) for 3 and 5 minutes. The results indicated that the highest surface hardness was achieved using the mechanical stirring method for Turkish beech with polyester varnish at 3 minutes of stirring (175.10), while the lowest surface hardness was observed for African mahogany with acrylic varnish and 120 watts ultrasound-assisted stirring for 5 minutes (66.80). The highest surface scratch resistance was observed in Scots pine treated with polyester varnish using mechanical stirring for 5 minutes (0.760 N), and in Turkish beech treated with acrylic varnish using 80 watts ultrasound-assisted stirring for 3 minutes (0.760 N). Overall, the findings suggested that the ultrasound-assisted mixing method generally fell short in terms of enhancing the varnish properties compared to the mechanical mixing technique.

Integrated wood surface densification and Al2O3/melamine impregnated paper coating process: Properties evaluation

Fast-growing wood is limited in its use due to its low density and poor strength. Strengthening its texture and enhancing its performance is crucial for maximizing the economic value of fast-growing wood. This study employed a one-step process of unilateral surface densification and coating, which involved compressing the surface of poplar wood and simultaneously applying Al2O3/melamine impregnated paper to achieve paint-free reinforcement modification. After modification, a cross-linking network structure was established at the interface of poplar wood and Al2O3/melamine impregnated paper with bonding strength satisfied superior product requirements for solid wood flooring as per GB/T 15036.1–2018. The natural texture and original aesthetic characteristics of poplar wood were preserved, the surface scratch resistance hardness was as high as 9 H, and the color and luster of the surface showed no obvious changes after being polluted by coffee and 25 % NaOH solution. Additionally, the functionalized wood also exhibited excellent mechanical properties with a modulus of rupture (MOR) of 112.6 MPa and a modulus of elasticity (MOE) reaching 9.33 GPa; the indentation diameter was only 7.5 mm, indicating excellent impact resistance, surpassing that of hardwood commonly used for wood flooring.

Ultra-high strength and high toughness 24CrNiMo alloy steel fabricated by laser powder bed fusion and subsequent quenching

A nearly fully dense grade 24CrNiMo alloy steel with superior comprehensive performance was fabricated by laser powder bed fusion (LPBF) under optimum laser parameters and subsequent quenching treatment was applied. The effect of quenching temperatures on microstructure evolution and mechanical properties of the LPBF 24CrNiMo parts were first systematically characterized and analyzed. The results demonstrated that the microstructure of LPBF 24CrNiMo steel (submicron grain size of 2.99 μm on average) was mainly constituted by block and stripe granular bainite containing twin substructure and θ-Fe3C carbides with no macroscopic segregation and anisotropy. After quenching, with the increase of quenching temperature from 800 to 1000 °C, the microstructure gradually changed from the acicular ferrite to martensite, finally to tempered martensite. The fine grains, the numerous twins were retained and the nanoscale carbides η-Fe2C were precipitated after quenching at 850 °C, simultaneously obtaining ultra-high mechanical properties including the hardness, yield strength, ultimate tensile strength and elongation were 446 HV and 1380 MPa, 1517 MPa, 13.8 %, respectively as well as the surface scratch resistance improved about 25 %. As quenching temperatures varied to 1000 °C, the mechanical properties lowered due to the coarsening and uneven distribution of the grain and θ-Fe3C carbides as well as the decrease in the number of twins. The improved mechanical properties via quenching treatment was attributed to phase transformation strengthening, grain refinement strengthening and precipitate strengthening.

Evaluation of the antiwear-ability/scratch-resistance efficacy of makeup products by in vitro test method application.

The objective of this study is to propose a method for assessing the antiwear-ability (AW) or surface scratch-resistance (SR) efficacy of makeup products through in vitro experiments. The method primarily involves measuring the change in weight as a means of evaluating the overall effectiveness. AW/SR effects are evaluated by applying a fixed amount of makeup product on artificial fake skin and comparing the weight difference after simulated friction/scratch. The in vitro results indicate that this method is easy to operate and yields repeatable data. It consistently reflects differences between samples when compared to clinical studies. This method effectively compares the AW/SR effects of makeup products and demonstrates utility in evaluating product efficacy and difference. It holds great scientific and practical value.

Performance of Impregnated Paper Decorated Blockboard Manufactured Using HDF as Equilibrium Layer.

In order to further improve the performance of impregnated paper decorated blockboard (ecological board), high-density fiberboard (HDF) was selected as the equilibrium layer to replace the commonly used poplar veneer. Results showed that the performance of HDF ecological board can be comparable to that of poplar veneer ecological board. It had good appearance quality, and its surface scratch resistance, surface wear resistance, water resistance and mechanical properties met the requirements of National Standard GB/T 34722-2017. The surface cracking resistance of the ecological board prepared with HDF as the equilibrium layer reached the highest level (grade 5), far better than that of the poplar veneer ecological board. This was because HDF was a relatively homogeneous material, and its dry shrinkage in both the transverse direction and along the grain direction was much lower than that of the poplar veneer. This characteristic of HDF made it possible to improve the dimensional stability and bending resistance of blockboard substrates under dry and hot conditions. The formaldehyde emission of the HDF ecological board was higher than that of the poplar veneer ecological board, but it met the formaldehyde emission requirements of indoor materials according to GB 18580-2001.

A Study on Surface Physicochemical Properties of Woods Treated in Emulsion of Waterborne Varnish with Sesame and Grape Seed Oil

Aims: An eco-friendly coating emulsion prepared with mixture of oils of sesame and grape seed and alkyd-based waterborne varnish. The prepared emulsion applied four different wood substrates (walnut, beech, cedar and fir) in order to be investigated for some selected surface properties.
 Study Design: Several test methods were used to evaluate surface physicochemical properties of the coatings. The results obtained may be suggested for the selection of the best varnish-emulsion formulation for the improvement wood substrates and could provide useful evaluation of the test methods employed.
 Methodology: The wood species of Beech (Fagus sylvatica), Walnut (Juglans regia), Cedar (Cedrus libani) and Fir (Abies nordmandiana) were selected for the investigation. Commercially available alkyd based waterborne varnish was supplied ready to use form.
 Both sesame oil (Sesamum indicum L.) and grape seed oil (Vitis vinifera L.) were obtained from a company that produces them by the cold press technique commercially. Both oils were used as supplied, without additional processing. These oils were added to varnish at 10% and 20% proportions (volume/volume). The 5 μl of distilled water (surface tension of 72.6 mN /m) was applied on wood surface by a sessile droplet method to measure surface contact angles. The surface hardness and scratch resistance of the cured varnish layers on wood substrates were measured with using pencil hardness test procedure according to ASTM-D-3363 standard. Cross cut test also conducted according to EN ISO 2409 standard.
 Experimental Findings: It was found that coated walnut samples show 9.8 to 13.5° higher contact angle values in all directions while other three wood samples only show marginally different values (0.1 to 4.3°). The highest contact value of 35.9° and 35.8° was found with samples of Wg20 and Wg10 which treated 20- and 10% grape seed oil proportions in varnish emulsion. The oils of sesame and grape seed typically contain various proportions of fatty acids fractions which are constituents of a carboxylic acid with a long, aliphatic tail. These groups could be created a strong bond in combination with alkyd resin on wood surface. However, the surface energy distribution show only marginally changes regardless of treatment levels and conditions. Therefore, there is not any clear advantage observed on surface wood surface energy levels with coating applications. For 10% grape seed oil/varnish emulsion conditions, the hardness of coated surfaces found to be 3H, 3H, 2H, 2H for walnut, beech, fir and cedar, respectively. At 20% grape seed oil/varnish coatings, all coating surfaces show H level range. For cross hatch experiments, marginally similar trend was observed with 10-and 20% grape seed oil/varnish and 10% sesame oil/varnish emulsion coated wood species. Moreover, it was ranked 2 for fir, ranked 3 for beech and ranked 4 for cedar wood at 20% sesame oil/varnish emulsion coatings. It is noticeable that a correlation was observed between cross cut and surface scratch resistance properties with coated surfaces.

Preliminarny studies on scratch resistance of the face shields surface of firefighting helmets

Nowadays, in rescue operations firefighters of the State Fire Service use firefighting helmets which protect their head. Type B helmets in accordance with PN EN 433 technical norm are most often used. The face shields of firefighting helmets are usually made of transparent polycarbonate. One layer of metalized coatings, usually made in PVD technology are often applied on the shield surface. Sometimes multi-layer and gradient coatings are also applied. The surface of a visor may get damaged. Surface damages limit the field of rescuer view, and also adversely influence on barrier properties of the shield. One of the utility criterion for face shields and glasses of firefighting helmets is scratch resistance. Comparative studies on scratch resistance of surface were performed. The test was conducted with the use of Rockwell diamond cone. Small differences in scratch resistance were shown. The mechanism of surface degradation due to scratch of studied shields were varied. The highest resistance against the indenter was obtained in case of the shield surface of the Kontekst helmet. The lowest surface degradation was observed for the helmet with the shield face covered by metalized coating - Gallet. The face shields of helmets without coating were characterized by higher dam-ages. The highest damage was obtained in case of the Kontekst helmet.

Mechano-tribological properties and in vitro bioactivity of biphasic calcium phosphate coating on Ti-6Al-4V.

Biphasic calcium phosphate (BCP) consists of hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP). BCP is mainly used in artificial tooth and bone implants due to higher protein adsorption and osteoinductivity compared to HA alone. Although, many studies have been investigated on radio frequency (RF) magnetron sputtering of HA on Ti and its alloy, however, limited studies are available on BCP coating by this process and its bioactivity and adhesion behavior. Thus, in order to obtain a better understanding and applications of BCP films, RF magnetron sputtering is used to deposit BCP films on Ti-6Al-4V in the present study. The effect of film thickness on wettability, mechanical properties and in vitro bioactivity at a particular set of sputtering parameters are investigated. BCP film thickness of 400 nm, 700 nm and 1000 nm are obtained when sputtered for 4 h, 6 h and 8 h, respectively. Although the phase compositions are almost same for all films, the surface roughness values varies around 112-153 nm with rise in film thickness. This in turn enhances hydrophilicity in accordance to Wenzel relation as the contact angle decreases from 89.6 ± 2° to 61.2 ± 2°. It is found that the 1000 nm film possess highest micro-hardness and surface scratch resistance. No cracking of film up to scratch load of 2.3 N and no significant delamination up to load of 7.8 N are observed, indicating very good adhesion between BCP films and Ti-6Al-4V substrate. There is a great improvement in wt% apatite layer formation on all films when dipped in simulated body fluid (SBF) for 14 days. Among these, 1000 nm sputtered film results the highest increase in wt% apatite layer from 44.87% to 86.7%. The apatite layer possess small globular as well as elliptical structure are nucleated and grew on all the BCP films. Thus, sputtering of BCP films improves wettability, mechanical properties as well as bioactivity of Ti-6Al-4V, which can be applied for orthopedic implants.

Mechanical and microstructural characterization of W–Cu FGM fabricated by one-step sintering method through PM route

Five layer W-Cu functionally graded material (FGM) for components in nuclear fusion application was fabricated by a one-step resistance sintering process, known as spark plasma sintering (SPS). In this study effect of sintering temperature (Ts) on physical, mechanical and surface property was investigated. Detailed microstructural study revealed that the graded structure of the composite layers with varying composition from 0 to 100 wt% W and Cu in opposite directions could be well densified after the SPS process. It also indicates that the fine microstructure within functionally graded layers can be maintained because of short sintering time. The sample sintered at 1050°C shows more than 90% theoretical density, hardness greater than 239±5 Hv and excellent surface scratch resistance. The result demonstrates that SPS is promising and more suitable process for fabrication of W-Cu FGM.

Effect of Additives on UV-activated Urethane Acrylate Polymerization Composite Coatings

An increased demand for new and improved coating systems, for environmental & health & safety and performance reasons, have appeared during the recent decades. Currently, there is new interest in preparation of thin UV curable urethane acrylate (UA) composite coatings with short-term properties. Cellulose based additives: nitrocellulose, cellulose acetate butyrate, sucrose benzoate and silica were evaluated to determine their influence on unreacted composite characteristics (viscosity, pigment suspension stability) and characteristics of cured film (ultimate tensile strength, elongation at break, surface gloss, surface scratch resistance and film adhesion loss time). The most suitable additive content was found to provide required viscosity. All additives increase surface scratch resistance, but cellulose based additives increase surface gloss values and decrease the time of adhesion loss. Silica has great effect on the interaction between linear and hyperbranched urethane acrylates, which has crucial influence on the stability of uncured pigmented mixture samples.

Wetting and other physical characteristics of polycarbonate surface textured using laser ablation

Surface texturing of polycarbonate glass is carried out for improved hydrophobicity via controlled laser ablation at the surface. Optical and physical characteristics of the laser treated layer are examined using analytical tools including optical, atomic force, and scanning electron microscopes, Fourier transform infrared spectroscopy, and X-ray diffraction. Contact angle measurements are carried out to assess the hydrophobicity of the laser treated surface. Residual stress in the laser ablated layer is determined using the curvature method, and microhardnes and scratch resistance are analyzed using a micro-tribometer. Findings reveal that textured surfaces compose of micro/nano pores with fine cavities and increase the contact angle to hydrophobicity such a way that contact angles in the range of 120° are resulted. Crystallization of the laser treated surface reduces the optical transmittance by 15%, contributes to residual stress formation, and enhances the microhardness by twice the value of untreated polycarbonate surface. In addition, laser treatment improves surface scratch resistance by 40%.

Environmental effects on initiation and propagation of surface defects on silicate glasses: scratch and fracture toughness study

The glass composition and surrounding environment can play an important role in the initiation and propagation of surface defects, which affect the practical strength of glass. We have studied how the environment and glass composition affect the tribological and indentation properties of multicomponent silicate glasses. Soda lime silica and aluminosilicate glasses were studied to compare the effects of the alkali ion and glass network type on surface defect formation. Although both glasses contained leachable sodium ions, the surface wear of soda lime glass decreased with increasing humidity while sodium aluminosilicate glass had an observable increase in surface wear. This indicated that sodium ion and water activity on/in glass surfaces vary depending on the glass network structure. The exchange of Na+ with K+ in aluminosilicate glass increased the elastic modulus, hardness, and resistance to fracture substantially; however, it did not improve the surface scratch resistance in humid environments. This suggested that the improved fracture toughness for the K-exchanged aluminosilicate glass is mainly due to the improved bulk properties; surface wear can readily take place regardless of Na/K-exchange.

Surface scratch assessment of titanium implant abutments and cementum following instrumentation with metal curettes.

This study was conducted to compare the surface scratch resistance of titanium implant abutments and cementum to evaluate the impact of scaling with metal curettes on both surfaces. A standard in vitro force of 14 N was used to assess the scratch width and depth created by curettes on extracted human tooth roots and titanium implant abutments. Scratch width and depth were analysed using a stereomicroscope and non-contact surface profilometry. The mean force applied during test scaling procedures by experienced volunteer operators was 14 N. Mechanical scaling using this force in vitro of cementum produced a mean scratch width of 59.4 ± 1.9 μm, N = 20, and scratch depth of 0.86 ± 0.03 μm, N = 20, compared to the titanium abutments' mean scratch width of 30.8 ± 1.9 μm, N = 6, and scratch depth of 0.34 ± 0.02 μm, N = 6. These differences were statistically significant (P < 0.05). Although there a number of factors in the clinical situation which are not easily reproducible in vitro, this proof-of-principle in vitro study is the first to confirm quantitatively that titanium abutments had a significantly greater scratch resistance than cementum when metal curettes were used on these surfaces. This information should be considered, especially if there is a preferred choice of metal instruments for effective dental prophylactic procedures for the maintenance of titanium dental implants. Clinical dogma suggests that titanium implant abutment surfaces should not be instrumented with metal instruments due to scratching of the surface. However, since cementum is softer than titanium, the logic of this tenet seems flawed. This study demonstrated for the first time that titanium abutments undergo less scratch damage during scaling with metal curettes than does cementum. Metal curettes may be used on titanium abutments with as much confidence as for root planing on natural teeth.

Preliminary Tribological Study and Tool Life of Four Commercial Drills

The mechanical and tribological properties of drill bits have a strong influence on the characteristics and performance of such tools. Today there are many different types and makes of drills available and their various characteristics influence their efficiency and, of course, their cost. In this preliminary project, four commercial drills were studied; multiple examples of two of the drills were tested. These were selected because of their price and characteristics from those available in the Mexican national market. The tools were submitted to a variety of characterization tests in order to determine their mechanical and tribological behaviors. The tests included hardness by indentation (both micro- and nanotesting), microabrasion by ball cratering, and scratch testing to determine the coating adherence and surface scratch resistance by novel scratch testing procedure. Additionally, the drills were analyzed by energy-dispersive X-ray spectroscopy (EDX), Rutherford backscattering (RBS), and scanning electron microscopy to determine the surface characteristics and composition. The tracks resulting from the tribological tests were studied by profilometry and optical microscopy. The performance of the drill bits was then tested using a vertical drilling machine under controlled conditions of fixed cutting speed, constant load, and drilling depth. The quality of the drilled holes was determined by measuring the difference between the upper and lower diameters of the holes. We found that the wear rate, measured by ball cratering, and the bulk hardness rather than the surface hardness of the drill bits correlated best with the drill performance and lifetime.

Surface failure mode evaluation of pure AlN and AlN with Al2O3(0.1 μm) oxide layer by microscratch testing

The surface scratch resistance, damage evolution and damage detection during microscratching of pure AlN and AlN with an Al2O3 oxide layer (∼0.1 μm) were investigated. The microscratch experiments were performed in a progressive load-ramped mode where the load was linearly increased from 0 to 3 N as the scratch progressed with a loading rate of 0.2 N/min. The experiments resulted to two different failure mechanisms; Ductile scratching and fracture dominated scratching. In the case of pure AlN, inconsistent different kinds of damages were found to initiate at low critical load measured as 0.30 N. This critical load was also found to decrease with increasing the surface roughness, material density and grain size of AlN. In the case of pure AlN with an Al2O3 oxide layer, the critical load for crack initiation was measured as 0.45 N, higher than pure AlN. This critical load was found to generate uniform discontinuous chipping. The distance between these defects decreased and the failure mode gradually transformed to continuous chipping as the scratch progressed. The surface modification of AlN with the use of an Al2O3 oxide layer was found to improve the tribological properties of AlN.

Adhesion and fracture of polymeric coatings

There are many important aspects of the performance of polymeric coatings, adhesion and fracture are included amongst them. Industry has devised numerous tests for the measurement of adhesive strength and coating toughness, but, all too often, these are ad-hoc and based on end-use. This limits severely any overall value from use of these procedures. In this paper an attempt will be made to consider a more fundamental approach to such matters and, in particular, to establish a technique for measuring procedures for adhesive strength and coating toughness that are independent of shape. In terms of adhesive strength, flexible laminates can be accommodated as well as rigid joints, and as such method of measuring either the interfacial work of fracture or the delamination toughness can be developed. In terms of coating toughness, ductilebrittle characteristics of the coating or surface scratch resistance can investigated. All of these methods are illustrated in the paper.

Scratching maps for polymers

The scratching technique has gained interest in recent times due to its varied applications to a number of engineering materials, especially for the evaluation of surface scratch resistance of plastics. Scratching provides a convenient and reliable means to investigate the mechanical properties of organic polymers under various contact conditions. The scratch hardness method is widely adopted to provide a first-order evaluation of the relative scratch resistance of materials for comparison purposes. The method also allows the identification and the assessment of the surface deformation processes and maps defining the scratch deformation modes as a function of contact conditions may be generated. These scratching maps may present experimental results in terms of the deformation mechanism, the scratch hardness and the friction coefficient. This paper primarily provides a review of the application of scratching maps for polymers. Results for the scratch hardness and the deformation mechanisms for a poly(methylmethacrylate) (PMMA), a poly(tetrafluoroethylene) (PTFE) and an ultra-high molecular weight poly(ethylene) (UHMWPE) are presented. The PTFE system is also described following the effects of γ-irradiation; radiation produces a marked reduction in toughness. The scratches were produced on the polymer surfaces by cones and spheres of various size under a number of contact conditions (e.g. applied normal load, strain, scratch velocity, etc.). SEM imaging and laser profilometry are used for the study of the deformation mechanisms and the measurements of the scratch profiles. It is shown that polymers exhibit a wide range of scratch deformation characteristics and that the deformation mechanism is determined by the most efficient energy dissipation process for the particular external constraints.