SiC Mold Research Articles

Modeling and prediction of surface topography and surface roughness in magnetic-field-enhanced shear-thickening polishing of SiC mold

To fill the gap in the research on the surface morphology formation theory of small aspheric magnetic-field-enhanced shear-thickening polishing (MESTP), a theoretical framework for surface morphology formation during the MESTP process was proposed for the first time. Based on the macroscopic computational fluid dynamics and convolution iteration theory, a multiscale surface morphology prediction model was established. This model considers the mechanical mechanism of the ductile-brittle transition of hard and brittle materials and effective cutting abrasive distribution law. Through a series of experiments and simulations, the maximum relative error between the measured Sa data and theoretical prediction data was 9.1%, and the accuracy of the model was analyzed based on RMSE. The proposed model can predict the microsurface morphology in MESTP.

Experimental investigations on weak magnetization-enhanced force-rheological polishing of SiC mold

Experimental investigations on weak magnetization-enhanced force-rheological polishing of SiC mold

Abrasion resistance of femtosecond pulsed laser processed micro molds of laser shock imprinting

Laser shock imprinting is highly efficient to manufacture functional thin films. However, the manufacturing process and the service life of the mold were the main issues that restrict its large-scale application. In this study, high-quality and high-precision periodic patterns were manufactured on aluminum foils of thickness 4 μm by laser shock imprinting with femtosecond pulsed laser etched Si and SiC molds. It proved that the micro molds with different patterns fabricated by variant femtosecond pulsed laser were able to tailor the optical function performance of the films. The effects of shock imprinting times on the abrasion resistance of different material mold were studied. The SiC mold with higher hardness has better wear resistance. The reflection rate attenuation of the film based on the SiC mold was obviously smaller than that on the Si mold after 100 times of imprinting. The difference performance caused by different molds was analyzed by elastoplastic mechanics of finite element method. The higher hardness of SiC suffer less wear and plastic deformation in the imprinting process, so it can mitigate the mold microstructure size degradation, which fabricates more accurate surface microstructures on the aluminum foils. The SiC is more suitable for making laser shock imprinting mold for future large-scale industrial application.

Experimental Study on a Microwave Composite Forming Process Based on a SiC Mold for Manufacturing Fiber Metal Laminate.

The microwave composite forming (MCF) process can reduce manufacturing cost because the process time is reduced by the dielectric heating of the mold and the composite material. In a previous study, the MCF process using a commercial microwave oven with a polytetrafluoroethylene mold was applied. Disadvantages of the previous MCF process have been investigated. These included the difference in tensile properties according to the cutting location, absence of a method to measure temperature during the MCF process, and the fact that the input power cannot be controlled according to the temperature. To solve these problems, a microwave oven with a silicon carbide mold was proposed in this study. Uniaxial tensile tests were conducted to obtain the tensile properties of the fiber metal laminate (FML) specimen. In addition, a microscopic image was captured to investigate the non-adhesive area. The tensile properties and thickness distribution of the FML specimens manufactured by the proposed and previous MCF processes were compared according to the cutting location of the FML sheets. Furthermore, the non-adhesive area was quantified to compare the processes. The results revealed that the proposed MCF process improved the tensile properties of the FML specimen and reduced the non-adhesive area.

Molecular dynamics study on friction property between fused silica and SiC mold in high temperature molding

The friction property between glass and mold have an important impact on the forming quality of optical components and working lifetime of the mold in the precision glass molding process. The effects of driving force, pressing force and temperature on the friction property between fused silica and SiC mold during high temperature molding were studied by molecular dynamics simulation. Two different surface nanostructures, semi-cylindrical and square column groove, were also considered. The velocity and density distributions as well as the structure information of fused silica were calculated in the process of flowing along SiC mold surface. The results indicate that flow rate, density and interatomic force are the three dominant factors which control the friction force by affecting amplitude change and transfer of momentum. Among them, the effect of interatomic force on friction is the most obvious. The study can help to provide the optimized parameters of precision molding of fused silica and improve the production quality of optical components.

Development and Precision Molding of Optical Glasses with High Refractive Index for Optical Applications

The structure and optical properties of phosphate glasses containing bismuth or niobium oxides for subwavelength structure (SWS) optical elements were studied. The glasses containing a large amount of bismuth and niobium oxides had refractive indexes higher than 1.8 and low deformation temperatures. However, these high refractive index glasses were yellowish due to the electronic transition in trivalent bismuth ions and pentavalent niobium ions. The structure of the glasses was investigated by X-ray, IR, and Raman spectroscopy. NbOx and BiOx formed clusters as the bismuth and niobium oxide content increased. The results showed that the local structure around bismuth and niobium ions was related to the coloration. Based on these results, we developed high refractive index glasses that were used for precision molding to fabricate periodic SWSs. One-dimensional periodic SWSs were fabricated on the glass surface by a precision molding method using a SiC mold on which the reverse of the SWS pattern was carved and a flat SiC mold. One-dimensional SWSs with a high aspect ratio were fabricated on one surface of the glass plate. The niobium phosphate glass plates with the one-dimensional SWS showed phase retardation higher than 1/8l between TE- and TM-polarized beams at 400 nm, demonstrating that a wavelength plate can be fabricated by our precision molding technique.

The Study on the Selectivity Ratio of SiC/Epoxy Resin Based on ICP Etching

SiC molds have excellent performance for high-temperature molding optical lenses. The stable physical and chemical properties of SiC results in the difficulty of manufacture high precision SiC molds. Using etching method can manufacture SiC molds apace and accurately, which is used for Micro-embossing needs to study the suitable selectivity ratio of SiC and the anti-etch layer-epoxy resin. The etching gas is SF6 and O2. Under different ICP power, bias voltage, the gas mixing ratio and other parameters, it has studied the influence of various factors on the etching ratio, the etching rate and the etching quality. Experiments show that under the parameters of SF6 flow of 80sccm, O2 flow of 5sccm, ICP power of 1200w, bias power of 70w, temperature of 30 °C, and pressure of 30mTorr, the SiC etching rate is 246.44nm/min, and the epoxy etching rate is 616nm/min. The SiC/epoxy resin etching ratio is stable at 1:2.5. The roughness of SiC is 1.2nm (Sa= 1.2nm). The anisotropic of etching is good.

Deformable silicone grating with submicrometer period

We fabricated a deformable transmission grating with a silicone elastomer [poly(dimethylsiloxane)], and evaluated its optical characteristics during a compression process. This grating pattern was created on a silicone surface by a polymer mold that had been fabricated by photo-imprinting process with an SiC mold to realize a simple, low-cost fabrication process. We also measured the relationship between the grating period and compressive stress to the fabricated elements. The grating periods of the fabricated elements were evaluated from the measured diffraction angles. The grating periods of 3.02 and 410 nm were changed to 2.86 µm pitch and to 368 nm pitch, respectively, by compressing the fabricated element in one direction, perpendicular to the grooves.

LOW-Tg BISMUTH PHOSPHATE GLASSES FOR GLASS-IMPRINTING AND FABRICATION OF 2D SUB-WAVELENGTH STRUCTURE

We have developed zinc-bismuth-phosphate glasses, which have deformation temperatures under 450°C and refractive indices higher than 1.7, in order to produce an antireflection structure on the surface by a glass-imprinting process. Two-dimensionally arrayed conical cavities of sub-wavelength size were fabricated on a SiC mold by electron lithography and dry etching techniques. The sub-wavelength periodic structure was transferred onto the glass surface by a glass-imprinting process using the mold. The sub-wavelength structure suppressed the reflectance by approximately 90%. A weak maximum was observed in the reflection spectra around 400–500 nm, which decreased in intensity and shifted toward shorter wavelengths with decreasing pitch.

Periodic sub-wavelength structures with large phase retardation fabricated by glass nanoimprint

One-dimensional periodic sub-wavelength structures (SWSs) with a period of 300 nm were fabricated on a bismuth germano-borate glass plate by a direct glass nanoimprint method using SiC molds. The borate glass had a refractive index of 1.82 at 587.6 nm wavelength, an internal transmittance higher than 80% at a thickness of 3 mm in the visible wavelength region, and a deformation temperature of 468°C. SWSs with height of a few hundred nanometers were simultaneously fabricated on both surfaces of the glass plate by the glass nanoimprint at 488°C for 120 s with 8 MPa in pressure. The SWSs showed form birefringence. A phase retardation of 0.23 λ was observed between transverse electric (TE)- and transverse magnetic (TM)-polarized beams at 400 nm wavelength.

Antireflective structure imprinted on the surface of optical glass by SiC mold

An antireflective structure with two-dimensional 300-nm periodicity was fabricated on a phosphate glass surface using an imprinting process with a SiC mold. The optimized structure designed using RCWA calculation was a convex circular cone sharing the ridge line of adjacent cones. The SiC mold was fabricated using electron beam drawing and subsequent reactive ion etching with CHF 3 and O 2 gases. The glass’ surface reflectance was estimated as 0.2% at 530 nm wavelength, which was approximately 1/20 that of the optically polished surface.

Site Control in Anodic Etching of Semiconductor Single Crystals by Direct Nanoimprinting Using SiC Molds

not Available.

Direct Nanoimprinting of Si Single Crystals Using SiC Molds for Ordered Anodic Tunnel Etching

Direct Nanoimprinting of Si Single Crystals Using SiC Molds for Ordered Anodic Tunnel Etching

Fabrication and Electrochemical Behavior of Nanodisk Electrode Arrays with Controlled Interval Using Ideally Ordered Porous Alumina

A novel process for the fabrication of Au nanodisk electrode arrays with controlled disk electrode separation is proposed. This process effectively overcomes the problem of overlapping diffusion layers around interdisks by ensuring sufficient disk separation. Using an SiC mold, an aluminum substrate was imprinted with an ideally ordered pattern with features at prescribed sites that were then selectively etched as through-holes for the deposition of Au. The fabricated Au disk electrode arrays exhibited sigmoidal voltammetric behavior, indicating that the array functioned effectively as an ensemble of single nanoelectrodes.

Ordered Arrays of Nanopillars Formed by Photoelectrochemical Etching on Directly Imprinted TiO2 Single Crystals

Arrays of TiO2 nanopillars have been prepared by photochemically etching a TiO2 single crystal that had been previously imprinted with a corresponding array of dimples using SiC molds. The pillars have a high aspect ratio (see scanning electron microscopy (SEM) image in Figure) and the method is simple and suitable for high‐throughput production.

Fabrication of ideally ordered anodic porous alumina with 63 nm hole periodicity using sulfuric acid

Nanochannel arrays with an ideally ordered hole configuration with a 63 nm hole periodicity and 15–40 nm hole diameter were fabricated using anodization of the pretextured Al in sulfuric acid solution. The SiC mold with an array of convexes, which was prepared by electron beam lithography, was used for the nanoindentation of the Al. The periodicity of convexes was adjusted to the self-organized periodicity in sulfuric acid solution. The obtained concaves on Al initiated the hole development during the anodization and generated the ideally ordered hole configuration with a 63 nm period. Under the appropriate anodization conditions, anodic porous alumina with an aspect ratio of over 20 was obtained.

63-nm-Pitch Pit Pattern Fabricated on Polycarbonate Surface by Direct Nanoprinting

Nanoscale pit patterns were formed on a polycarbonate substrate surface, which is commonly used for compact disks, by direct nanoprinting. Pit patterns with 100, 70, and 63 nm pitches were imprinted on the disk surface using a SiC mold with a nanostructure projection pattern. These pitches correspond to the the storage densities of 75, 150, and 185 Gbit/in2. We evaluated the mold-holding temperature and press-pressure dependence of the pit depth. We also evaluated the press-time dependence. With a relatively low press-pressure of 1.3 kg/mm2 at room temperature, a 100-nm-pitch pit pattern with a pit depth of over 40 nm was fabricated using a mold with a projection height of 60 nm.

Direct nano-printing on Al substrate using a SiC mold

Nanostructures in Al were generated by printing with hard SiC molds. This nano-printing technology replaces the lithography and the etching or deposition processes to produce patterns directly in metal. Dots, short lines, and long lines were formed in the SiC molds by electron beam lithography and reactive ion etching. High aspect ratio features as small as 40 nm with depth up to 840 nm were patterned in the SiC molds. By pressing the SiC mold onto the Al substrate at room temperature, nanostructures in the SiC mold were reproduced accurately and uniformly in Al. Large arrays of nanostructures down to 40 nm were printed in Al with similar results for dots, short lines, and long lines. Using atomic force microscopy to analyze the cross sections of the SiC molds and printed Al nanostructures, depth dependence on feature size was observed. This nano-printing technology simplifies the processes for generating nanostructures with high throughput and high uniformity.

Hot pressing of large PLZT slugs

Abstract Large (diameter ≥ 100 mm) transparent PLZT slugs may be fabricated by green pressing PLZT powder into a cylindrical compact which is placed atop an aluminum base plate, surrounded by a SiC mold, and subjected to a pressure of 6.9 MPa while heating to 700°C in an evacuated chamber. Ozygen is then admitted to the chamber, and after a three-hour hold the pressure is raised to 13.8 MPa and the temperature to 1250°C. After a hold of 18 hours, the temperature is slowly lowered to ambient.

A hot pressed coprecipitated ferrite and its application to magnetic heads

The nature of a coprecipitated ferrite powder has been studied and a hot pressed coprecipitated ferrite has been developed. A superior material, although hot pressed in air, was assumed due to a homogeneity of the powder, a partial oxidation of the powder and a low green density. A partial oxidation at 700°C in air decomposed the powder into a deformed spinel, α-Fe 2 O 3 and unknown phases and yet a microscopic homogeneity was not lost. This led to an easier control on sintering by reducing an excessive reactivity of the powder and introducing a reaction sintering. A low green density of less than 2 g/cm3resulted in a slow sintering and thus oxygen evolved at the initial sintering stage was not trapped in a sintered body and a reaction sintering permitted a high degree of densification. A continuous grain growth and an oxydizing atmosphere at an initial sintering stage contributed to segregate pores mainly at grain boundaries. A small grain size (about 50μm in average) and a reducing atmosphore of a SiC mold subsequently at high temperature were also effective and a hot pressing further reduced a porosity less than 0.05%. An appropriate reducing atmosphere also improved a permeability at 5MHz to 1000. Due to a high permeability and also due to an improved microstructure and thus a superior precission machinability, magnetic heads made of the new HPF exhibited twice as much output at 5MHz as the conventional one.