ナノ周期積層膜の摩耗特性を活用したナノ加工技術の開発

An appropriate clearance is required between mating gears for effective power transmission. In the present work, the effect of radial misalignment on mild wear of spur gear is modeled and simulated. The changes in the gear tooth contact geometry due to progressive wear have also been accounted in the model. The simulation results show that in the pinion dedendum region, pressure angle increases, while the contact pressure and wear depth decrease with increase in number of wear cycles. As far as the effect of radial misalignment is concerned, contact pressure decreases and wear depth increases with the increase in misalignment. In the pinion addendum region, pressure angle and wear depth increase with the increase in wear cycles, while the contact pressure and wear depth decrease with the increase in misalignment. The pressure angle and pitch point change from initial 20° (23rd pitch point) to 20.95° (26th pitch point) and 21.86° (28th pitch point) due to 0.5- and 1-mm radial misalignment, respectively. The wear depths after 50,000 wear cycles are − 1.32 × 10−2 μm, − 3.33 × 10−3 μm and − 4.39 × 10−4 μm at 23rd, 26th and 28th pitch points, respectively. The effect of radial misalignment on backlash, pressure angle, pitch point, contact ratio, double tooth contact region and speed ratio is also discussed.

Tribology of carbon nitride and boron nitride nanoperiod multilayer films and its application to nanoscale processing

Wear and fatigue resistance: An in-vitro comparison of three polyethylene terephthalate glycol and thermoplastic polyurethane materials for vacuum-formed retainers

The effect of 200 days of cyclic weathering test (CWT) and 1,000 h of salt spray test (SST) on the performance of polyurethane (PU) coating was investigated. A 200 μm coating was applied to a composite and cured before CWT and SST ageing studies. CWT was conducted in ten cycles (each cycle: −40°C for 5 days, 70°C for 5 days, 40°C and 90% RH for 5 days, and salt fog for 5 days). Initial water immersion tests concluded that the coated specimens have 37% less water absorption than uncoated specimens. The degradation behaviour of the coating was evaluated by measuring pull-off adhesion strength, critical load from the scratch test, and wear depth from the pin-on-disk test. Similarly, the surface characteristics of the coating were studied by SEM, gloss value, and contact angle. CWT ageing caused a decrease in gloss value (93–78 GU), pigment content (18–8 wt%), contact angle (92–70°), and an increase in wear depth at 20 N of applied load (45–200 µm). Similarly ageing also decreased the pull-off adhesion strength to 6.77 MPa (CWT) and 7.93 MPa (SST). CWT and SST also decreased the thermal stability by 11–13°C, considering 5 wt% loss and tensile strength of the coating from 42 to 29 MPa. The damage to the composite substrate was not significant due to prolonged exposure periods under CWT and SST, though the damage was noted in PU coating, like increased surface roughness and wear depth.

ABSTRACT: In the process of exploration and development of extended-reach wells and ultra-deep wells, serious dogleg severity and high hardness formation, etc. will lead to casing exterior wear, thereby reducing the residual strength of the casing. However, the existing research on casing wear mainly studies the interior wear of casing caused by the rotation of drill pipe joints, and ignores the exterior wear caused by the contact between casing and well wall during casing running. As a consequence, the prediction model of casing exterior wear is established based on the wear efficiency model and the three-dimensional torque and drag model. Case study is conducted with this model and sensitivity analysis is also performed. The results show that the casing with the greatest exterior wear depth is located below the direction turning section. The wear depth decreases with the increase of the outer radius of the casing, and increases with the increase of the wellbore radius. In addition, with the increase of drilling fluid density, the wear depth of the upper casing increases, and the wear depth of the lower casing decreases. The casing collapse resistance after casing exterior wear is studied through numerical simulation. The results show that the collapse resistance of casing decreases with the increase of wear depth, and there is an approximate linear relationship between the two. The study provides a method to improve the prediction accuracy of casing wear, which is of great significance for the casing design and wellbore integrity. 1. INTRODUCTION With the development of drilling technology, horizontal well and extended reach technologies are widely used in the world. The wellbore conditions of extended-reach wells and horizontal wells with long horizontal sections are more complicated than conventional wells. Running casing is challenging due to the difficulty of hole cleaning, the high friction factor, the wellbore tortuosity, and the large lateral force acting on the wellbore by the casing, etc. Usually the casing needs to be picked-up and released many times, and the running time is long, so the outer wall of the casing is more likely to be worn, which reduces the residual strength of the casing.

A previously developed micromagnetic model for single-layer thin-film recording media is extended to model multilayer thin-film media. Effects of the magnetostatic interactions between the adjacent magnetic layers in the film are studied for a film with two magnetic layers separated by an ideal nonmagnetic layer. Magnetization reversal processes and hysteresis properties are studied for films with different separation layer thicknesses. It is found that the magnetostatic interaction between the two adjacent magnetic layers in the multilayer films with an ideal thin nonmagnetic interlayer can result in significant changes of micromagnetic behavior within each magnetic layer. This micromagnetic modeling study explains why reducing the separation thickness can yield further reduction of the medium noise.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Carbon and boron nitride nanoperiod (C/BN)n, boron nitride and carbon (BN/C)n, carbon nitride and boron nitride nanoperiod (CN/BN)n, and boron nitride and carbon nitride (BN/CN)n ]multilayer films with a 4-nm-period multilayer structure were deposited by bias radio frequency (RF) sputtering. The substrate used for deposition was repeatedly positioned opposite graphite and boron nitride targets. Both the nanoindentation hardness and microwear resistance of the multilayer (CN/BN)n and (BN/CN)n films changed with the layer period. The multilayer films with a 4 nm period had the highest hardness and microwear resistance. The processing characteristics of the (C/BN)n and (BN/C)n films with a 4-nm-period multilayer structure were investigated using a conductive atomic force microscope (AFM) with force modulation, which permits the quantitative recording of current and frictional force as functions of applied force. The results of processing indicated that friction and surface-current measurements are effective methods of investigating multilayer nanostructural surfaces and that the method proposed in this study for micro-electro-mechanical processing systems has high precision.

The influence of the particle size of fillers on the frictional wear properties of dental composite resins has been investigated. Five kinds of silica fillers with mean particle sizes of 0.5, 3.3, 4.3, 7.9, and 15.5 μm are used in this study. The filler volume is kept constant at 70 wt%. The coefficient of friction between the abrasive and the specimen was determined by a frictional wear device employing a rotating wheel. After the test, the wear depth was measured by a surface profilometer and the wear surface was observed by FE-SEM. The results demonstrate that the coefficient of friction and the wear depth increase with an increase in the particle size of the filler of composite resins. In addition, a linear correlation between the coefficient of friction and wear depth was found.

Evaluation of friction and wear depth during the cyclic loading on partly melted LPBF particles of LPBF Cu alloy

A polynomial approach is adopted to simulate the optical-electrical response of a multilayer thin film subjected to an applied transverse voltage. Each layer in the thin film is modelled by a propagation matrix, while the coupling between any two adjacent layers at an interface is modelled by an interface matrix. Each layer in the multilayer thin film in the present approach is treated as a capacitor coupled to the next so that the multilayer film is modelled as an effective capacitor which is constructed by a series of coupled capacitors. The electric charges accumulated at the interface between adjacent ‘capacitors’ can be modulated by the transverse voltage. The model is constructed to describe only lossless and nonmagnetic materials. The reflection and transmission of multilayer MgO/CaF2 thin films with a selected number of layers and structure, subjected to a tunable transverse potential, are simulated with a home-grown code implementing the model. The numerical results indicate that non-trivial optical responses can be conveniently predicted with the code, providing a handy simulator for designing and optimizing desired optical functionality of an arbitrary lossless multilayer thin film by tuning the transverse potential and the geometrical and electrical parameter of the structure.

Wear resistance of 3D printed, milled, and prefabricated methacrylate-based resin materials: An in vitro study.

Ion-beam-assisted deposition (IBAD) was investigated as a potential way to increase the fretting fatigue resistance of Ti-8Al-1Mo-1V alloy at elevated temperature. Three coating systems, hard TiN film with good toughness and soft Al film of low friction and Cu/Ni multilayer films with modulation period thickness of 20~600nm have been applied on the base material. Coefficients of friction and fretting fatigue lives of the specimens with and without film were compared. The film damage was characterized through scanning electron microscopy. The results indicate that the IBAD technique can prepare all films with high bonding strength and excellent lubricating properties. The fretting fatigue life of the Ti-8Al-1Mo-1V alloy with the TiN film was improved by a factor of 2.4 as compared to the uncoated substrate at elevated temperature because of the excellent wear and fatigue resistance and good toughness of the film. Excellent wear resistance and good anti-fatigue properties could be simultaneously obtained by a single hard film to control the fretting fatigue damage. The IBAD Al film significantly improved the fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy at elevated temperature for good lubricating property. The fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy was improved by all the Cu/Ni multilayer films. However, the fretting fatigue resistance did not increase monotonically with the modulation period of the films. Films with a modulation period of 200 nm had the highest fretting fatigue resistance among the multilayer films prepared owing to their high toughness and strength and good lubricating and anti-fatigue action. The fretting fatigue resistance of films with a modulation period of 20 nm was low because of the poor fracture toughness and crack propagation resistance, even though these films had the highest hardness and good fretting wear resistance. Thus, comprehensive properties, including high toughness and strength, must be considered for multilayer films used to improve the fretting fatigue resistance of titanium alloys.

The polypropylene/poly(vinyl alcohol)/polypropylene (PP/PVA/PP) multilayer active films with controlled release property were developed, of which the intermediate PVA layer was incorporated with 4% (w/w) tea polyphenols (TP) and the microporous PP films with different pore size were used as the internal controlled release layer. The SEM results showed that each layer of these films was agglutinated tightly. With increasing pore size from 171.05 to 684.03µm, there were little effect on the films' color and opacity, the tensile strength (TS) and elongation at break (EAB) decreased slightly, the gas barrier (O2 and water vapor) property of the film reduced faintly, the time of achieving the release equilibrium in 50% ethanol decreased from 75hours to 30hours. The diffusion coefficient for the films increased with the increase of pore size, from 2.06 × 10-11 cm2 /s to 8.06 × 10-11 cm2 /s, suggesting that the release rate of TP increased as the pore size increased. The results were indicated that its release rate could be controlled by adjusting the size of pore. The films also exhibited different antioxidant activities due to their different release profiles of TP. It showed promise for developing the controlled release active packaging film based on this concept. PRACTICAL APPLICATION: Controlled release packaging is propitious to extension of food shelf life. The microporous polypropylene films with different pore size used as the internal layer of polypropylene/poly(vinyl alcohol)/polypropylene (PP/PVA/PP) multilayer active films was proved that the release rate of tea polyphenols in the intermediate PVA layer released from the films into the food simulant can be controlled by adjusting the size of pore in this study. It showed a good prospect for using microporous or perforation-mediated film as the internal layer of multilayer film to develop the controlled release active packaging film for food packaging.

The structural and dielectric properties of SiO x/a-C,F/SiO x multi-layer thin films deposited by microwave electron cyclotron resonance plasma method

30CrNi2MoVA steel demonstrates excellent performance, meeting the requirements of a crucial material for high-load structural parts. However, after experiencing high loads and thermal cycling, the material undergoes wear on its contact surfaces, resulting in a certain wear depth that determines its service life. Therefore, accurately predicting and evaluating the wear performance and wear depth of this material is of paramount importance. This study employs a combined approach of experimental and simulation methods. Initially, friction and wear tests were conducted to investigate the wear behavior of the 30CrNi2MoVA steel. The experimental results reveal a significant influence of thermal cycling temperature on the material’s wear resistance, with wear mechanisms primarily attributed to adhesive wear and abrasive wear. Subsequently, a ball-on-disc wear model was established. Based on experimental data, the modified Archard model was implemented as a user subroutine in finite element software (ABAQUS version 2020) to assess the material’s wear volume. The simulation results demonstrate a close agreement with the experimental wear depths. Furthermore, a fitting formula was developed to correlate the wear depth of the material with the number of wear cycles, enabling accurate wear depth prediction. This study provides theoretical support for enhancing the performance and extending the service life of 30CrNi2MoVA steel.