Glass Mold Research Articles

Application of ta-C Coating on WC Mold to Molded Glass Lens

Application of ta-C Coating on WC Mold to Molded Glass Lens

Refractive index dependent optical property of carbon dots integrated luminescent solar concentrators

Abstract Colloidal Carbon dots (C-dots) have been used as promising emitters for luminescent solar concentrators (LSCs) due to its high quantum yield, low-cost, non-toxic and simple synthetic method. While it is still very challenging to fabricate high-efficiency LSCs based on C-dots because of strong spectral overlap between the absorption and emission. It is still unclear how the refractive index of the C-dots layer affects the optical properties of LSCs. Here we used liquid junction LSCs as an example to investigate the refractive index effect. A large-area (∼100 cm2) LSC was fabricated by injecting C-dots/polyvinylpyrrolidone solution into a glass mold. The refractive index of the polymer solution can be well controlled in the range of 1.33–1.44 by simply enhancing the polymer concentration. The reabsorption energy loss and the optical efficiency of the LSCs are strongly dependent on the refractive index of the polymer solution. The LSC based on C-dots/polymer exhibits refractive index dependent optical efficiency, as high as ∼0.92% under sunlight illumination, which is 27% enhancement in efficiency over the LSC based on C-dots dispersed in methanol.

English

This contribution presents the shape optimization problem of the plunger cooling cavity for the time dependent model of pressing the glass products. The system of the mould, the glass piece, the plunger and the plunger cavity is considered in four consecutive time intervals during which the plunger moves between 6 glass moulds. The state problem is represented by the steady-state Navier-Stokes equations in the cavity and the doubly periodic energy equation in the whole system, under the assumption of rotational symmetry, supplemented by suitable boundary conditions. The cost functional is defined as the squared weighted L2 norm of the difference between a prescribed constant and the temperature of the plunger surface layer at the moment before separation of the plunger and the glass piece. The existence and uniqueness of the solution to the state problem and the existence of a solution to the optimization problem are proved.

The Mediated Machine: Embracing Digital Technology as a Glass Artist and Student

In this essay the author discusses the benefits of introducing digital making tools into the glass artist’s practice-based research, both on a professional and student level. Using an example from his personal creative practice as a case study, the author outlines not only the practical benefits of using digital technology, but how when combined with traditional hot-worked glass techniques the synthesis can produce art objects that would otherwise be impossible using either digital or manual means alone. He argues that it is the possibility of inventing novel approaches to art making that can motivate glass artists and students to embrace digital means of making, rather than relying on appeals to practicality and efficiency alone. Includes a description of producing blown glass sculptures that combine fused water-jet cut sheet glass with traditional mold blowing and glass sculpting techniques.

Selection of Preform in Glass Molding Press of Aspherical Chalcogenide Lens

Glass molding press (GMP) is an effective method of mass production of glass lens, especially for chalcogenide glass lens. During the process of GMP, the preform is another key factor to achieve a good yield rate except the molding parameters. Three kinds of preforms are provided to conduct the molding experiment, which are made from the same material of chalcogenide glass. The first one is of the rough double-spherical surfaces, and the second one is turned by diamond cutting tools, and the last one is polished as smooth as possible. At the same conditions of 315°C heating temperature and maximum pressing force of 0.7MPa for 45s, only the polished preform can be pressed into a qualified aspherical lens, which has a shape accuracy of 0.875um and of 0.625um in peak-valley (PV) for concave and convex surface, respectively.

Influence of Glassy Carbon Surface Finishing on Its Wear Behavior during Precision Glass Moulding of Fused Silica

Laser technology has a rising demand for high precision Fused Silica components. Precision Glass Moulding (PGM) is a technology that can fulfil the given demands in efficiency and scalability. Due to the elevated process temperatures of almost 1400 °C and the high mechanical load, Glassy Carbon was qualified as an appropriate forming tool material for the moulding of Fused Silica. Former studies revealed that the tools’ surface finishing has an important influence on wear behaviour. This paper deals with investigation and analysis of surface preparation processes of Glassy Carbon moulds. In order to fulfil standards for high precision optics, the finishing results will be characterised by sophisticated surface description parameters used in the optics industry. Later on, the mould performance, in terms of wear resistance, is tested in extended moulding experiments. Correlations between the surface finish of the Glassy Carbon tools and their service lifetime are traced back to fundamental physical circumstances and conclusions for an optimal surface treatment are drawn.

WEDM-LS processing sophisticated and durable Zr-based metallic glass mold insert for micro structure injection of polymers.

Micro components processed by injection molding still have a defect of bad precision and short life. A Zr- based metallic glass was reported for injection mold insert which can solve the problem well. The microstructure of metallic glass mold insert can be fabricated by wire electrical discharge machining-low speed (WEDM-LS), WEDM-LS has higher machining accuracy than WEDM-high speed, and X-ray diffraction curves show that the processed sample still retained better amorphous characteristic, afterward, time-temperature-transformation diagram shows metallic glass has a long service life in production. Finally, under the observe of scanning electron microscope, it is found that the products after injection molding not only completely replicates the structure on metallic glass but also have a better surface morphology. These experiments show that processing a sophisticated and durable Zr-based metallic glass mold by WEDM-LS is good for getting micro structure injection of polymers. It also provides a good mold material and machining method for injection industry.

Comparison of fly cutting and transverse planing for micropyramid array machining on nickel phosphorus plating

Nickel phosphorus (Ni-P) is a promising plating material for the moulds used in the precision glass moulding (PGM) of micropyramid structure components. A transverse planing method for machining Ni-P moulds with a micropyramid array pattern is analysed. Notable defects, including chippings and burrs, are observed on the exit and entry parts, respectively. The defect-forming mechanisms are analysed, and it is confirmed that a large cutting thickness and chip interference in non-free cutting tend to be the most effective methods for eliminating defects. Based on the above analysis, the diamond fly-cutting method is introduced into the micropyramid array Ni-P mould fabrication process. The advantage of the diamond fly-cutting method is revealed through comparison with the transverse planing method. To establish a contrast to the transverse planing method and evaluate the machining quality of the structure in the diamond fly cutting, a maximum effective cutting thickness of the remaining surface is proposed based on theoretical analysis. Finally, an experimental setup of ultraprecision fly cutting is established, and an ultraprecision micropyramid array is fabricated on nickel phosphorus plating.

A Contribution to an Understanding of Complexing Agents and Salt Solutions Reaction Mechanism on Chemical Attack of Type I Molded Glass Containers.

An enhancement of the glass surface chemical attack was shown in type I molded borosilicate glass containers because of the synergy between the presence of complexing agents in the aqueous solution and basic pH. However, flake development (delamination) is not easily correlated with even a strong glass surface chemical attack. A few homologue series of carboxylic and dicarboxylic acids were investigated. We considered the presence of functional groups (NH2, COOH, OH), alkyl chain length (three to six carbon atoms), and C=C bonds. Tests were performed at 0.024 M constant concentration, in the 5.8-10 pH range, in small-volume 23 mL type I molded glass containers, and by autoclaving for 1 h at 121°C. The extracted silicon data confirm that both the dissociation constant pKa and the molecular structure of the complexing agent are determinant enhancing factors of glass surface chemical attack. The second part of the work concerned the glass surface chemical attack in the 5.8-9 pH range by alkali chloride solutions (NaCl and KCl 0.9% w/v and 0.0154 M) widely used in parenteral therapies. This last study was extended to also include LiCl and CsCl, even if they are not used in injectables, to evaluate a possible influence of the molecular weight on the glass chemical attack. A correlation between alkali chloride's molecular weight and glass chemical attack as a function of pH was found. Therefore, in a preliminary way, the complexing powers of acetic acid and EDTA (ethylenediaminetetraacetic acid) were examined in the presence of Na or Li ions, which showed different chelating propensities as a function of the alkali ion. The present research provides valuable information to the chemists involved in new pharmaceutical formulation to consider some possible compatibility limitations with the packaging in type I borosilicate glass containers.LAY ABSTRACT: The glass surface degradation particles appearing in vials (delamination) has forced a number of drug product recalls in recent years. Some drug formulations can contain active components or excipients with a known ability to corrode glass silica networks. Sometimes these ingredients are dissolved in an alkaline medium that dramatically increases the glass corrosion and potentially causes the issue. Flaking may become visible after a long period of storage; it could be affected by the surface glass composition but no correlation even with strong glass surface chemical attack was found. Generally, the synergy of complexing agents and concentrated salt solutions at alkaline pH increases the glass attack rate. The glass attack rate was investigated by analyzing extracted silicon in aqueous solution under controlled test conditions (autoclaving for 1 h at 121°C), in the 5.8-10 pH range, by a homologue series of 0.024 M solutions of complexing agents with different functional groups, alkyl chain lengths, etc. Data showed that both complexing agent acid dissociation constant, pKa, and molecular structure are determinant enhancing factors for glass surface chemical attack. The role of alkali chloride solutions at constant concentration and molarity was also examined.

Nanostructured DLC Coating for Protection of Dies from Wear

A traditional DLC coating has been designed to control its contents of sp2, sp3, and hydrogen atoms as well as the additive elements. In addition to this concentration control, both the density and cluster of carbon substructures were important in the advanced DLC coating design. Two types of nanostructuring were proposed to control the mechanical properties and tribological performance of DLC coatings; e.g., nanolamination and nanocolumn formation. In the former, a DLC-film consisted of multi-stacked sublayers with different densities to prolong the die life. In the latter, the nonlinear elasticity of low density carbon columns with high density carbon inter-columns, prevents the glass mold stamping die from adhesion to oxide glass.

The simulation of production performance – a case study

The article presents the possibilities of using a computer simulation to analyze a selected production process. The research was carried out based on data from the plant producing shaft packages from ready glass molds. The simulation takes into account the availability of machines and the average repair time for individual machines. An exemplary model was presented and various organizational and logistic solutions were analyzed. The conducted simulations allowed for direct identification of areas of increased efficiency. The solution to the highest process efficiency was indicated.

Investigation and modeling of microgrooves generated on diamond grinding wheel by abrasive waterjet based on Box–Behnken experimental design

Precision profile grinding with textured diamond wheels is an alternative for generating microstructures on the ceramic mold for glass molding. In this work, a novel texturing strategy employing abrasive waterjet for superabrasive grinding wheels was proposed to generate controllable microtexture profile on the diamond wheel surface efficiently. The quadratic backward-eliminated regression models were developed using Box–Behnken response surface design in the abrasive waterjet micromachining of diamond grinding wheel sample. The effect of operating parameters and their interaction on the depth and width of groove were investigated. The surface speed and standoff distance were found to be main controlling variables on the depth and width of groove, respectively. A consistently good agreement was confirmed between the predicted values and the experimental values under acceptable errors.

Preparation and properties of anion exchange membranes based on spirocyclic quaternary ammonium salts

<p indent=0mm>Among various types of fuel cells, alkaline anion exchange membrane fuel cells (AEMFCs) have attracted enormous attention as clean and highly efficient energy conversion devices for vehicles and portable electronic applications. As the key component of AEMFCs, anion exchange membranes (AEMs) act both as a barrier to separate the fuel and an electrolyte to transport hydroxide anion. To fulfill the application of AEMFCs, an AEM should possess good thermal stability, good mechanical properties, high conductivity and excellent alkaline stability. The lack of commercially available AEMs with excellent alkaline stability is limited the application of AEMs in the AEMFCs. In the recent years, a variety of AEMs based on poly(sulfone)s, poly(styrene)s, polypropylene, poly(arylene ether)s, poly(phenylene)s, poly(phenylene oxide)s and poly(olefin)s, have been synthesized for the application of AEMs. Most of these AEMs showed a similar chemical structure that a polymer backbone with with pendent quaternary ammonium cations. However, quaternary ammonium cations are unstable in alkaline environment due to the Hofmann degradation, the nucleophilic substitution and the ylide reaction, even in high temperature. Therefore, various types of AEMs based on some potential alternative cations, including imidazolium, guanidinium, phosphonium, metal-cation, pyridinium, tertiary sulfonium, and pyrrolidinium cations have been prepared and investigated in the last few years. Recently, different quaternary ammonium small molecules were synthesized and their alkaline stability was thoroughly investigated by Marino and Kreuer. Their study showed that spirocyclic quaternary ammonium have good stability in alkaline condition. To date, there is few work on spirocyclic quaternary ammonium-based AEMs, and to understand the properties of this type of AEMs, a systematic study is needed. In the present work, <italic>N</italic>,<italic>N</italic>-diallylpyrrolidinium bromide [DAPy][Br] was synthesized and used as hydrophilic phase in the polymeric membranes. The purity and chemical structure of [DAPy][Br] were confirmed by ¹H NMR measurements. However, poly(<italic>N</italic>,<italic>N</italic>-diallylpyrrolidinium bromide), the homopolymer of [DAPy][Br], shows poor film forming properties, and it is very soluble in water. Therefore, styrene and acrylonitrile were chosed to synthesize the copolymers with [DAPy][Br] due to the ease of processing, good mechanical properties and chemical resistance. A mixture of styrene/acrylonitrile, [DAPy][Br], divinylbenzene and benzoin ethyl ether was stirred to obtain a homogeneous solution. Then, the mixture was casted onto a glass mold irradiation with UV light. The prepared spirocyclic quaternary ammonium-based membranes were immersed in <sc>1 mol/L</sc> KOH solution at 60°C for <sc>24 h</sc> to convert the anion of membrane from Br^- to OH^-. Then the membranes was immersed in deionized water and washed with deionized water until the pH of residual water was neutral. In summary, a series of spirocyclic quaternary ammonium-based AEMs were successfully designed and prepared via a simple synthetic strategy. The resultant AEMs demonstrated great potential for alkaline anion exchange membrane fuel cell applications based on its good thermal stability, sufficient mechanical properties and high conductivity. The ion exchange capacity can be controlled by change the mixture ratio, and the swelling ratio, water uptake and ion exchange capacity of the spirocyclic quaternary ammonium-based membranes increase with the increasement of the content of [DAPy][Br] in the membranes. The transparent and mechanically robust spirocyclic quaternary ammonium-based AEMs show high conductivity up to <sc>7.29×10^-2 S/cm</sc> at 80°C, and all the membranes showed conductivity up to <sc>1×10^-2 S/cm</sc> at room temperature. In addition, all the AEMs synthesize in this work showed excellent long-term alkaline stability at elevated temperature. The spirocyclic quaternary ammonium-based AEMs with an aliphatic backbone exhibit high alkaline stability, which will open up new prospects for the preparation of AEMs with excellent alkaline stability and high conductivity.

Investigation on the surface formation mechanism in micro milling of cemented carbide

Cemented carbide is widely applied in optical glass molding process due to its excellent properties. The surface quality of cemented carbide mold is directly related with the glass element quality, mold life and production cost. In this paper, micro milling experiments were conducted on cemented carbide to investigate the surface formation mechanism. The surface morphology characteristics of different material removal modes were compared. Both the surface formation mechanism and damage behavior during micro milling process were analyzed in detail. The machining parameters selection strategy was suggested to obtain the high material removal rate and smooth surface quality. The surface quality was found to be less affected by the machining parameters when cemented carbide is removed with ductile mode than brittle mode.

The Fracture Resistance of Fiber Reinforced Composite Restorative Material has Higher Yield than Nanohybrid Resin Composite

Restorative materials used in dentistry should have aesthetic appeal and good strength for use in restorations on anterior and posterior teeth. Nanohybrid resin composite is a composite resin with nano-filler particles having both aesthetic appeal and good durability against fracture. The newest composite resin, fiber-reinforced composite, comprises resin matrix, E-glass fiber and organic particulate filler. Composite resins with E-glass fibers are expected to have higher fracture toughness values than composite resins without E-glass fibers. This research aimed to study the difference in the fracture toughness between nanohybrid resin composite and fiber-reinforced composite. Twenty samples were divided into 2 groups: Group I-nanohybrid resin composite and group II-fiber-reinforced composite. Each sample was applied incrementally on a glass mould and individually exposed to light for cure stiffening for 20 s. Before polymerisation of the second layer, the central part of the sample was given a sharp crack. The sample was then maintained at 37°C for 48 h, followed by testing for fracture toughness by the universal testing machine specification. Independent t-test revealed significant differences in fracture toughness values between the two groups (p = 0,000).

Study on the tool wear and its effect of PCD tool in micro milling of tungsten carbide

Tungsten carbide is the most promising material to produce glass molds due its unique properties. This paper conducts an tool wear experiment on PCD micro end mill in micro milling of tungsten carbide. The tool wear characteristics are observed and tool wear mechanisms are analyzed. The results show that PCD tool wear is concentrated on the tool tip, and a triangular wear belt is formed on the tool bottom surface. The involved tool wear mechanisms mainly include the adhesive wear, micro chipping and abrasive wear. After PCD tool is worn, the cutting forces is increasing, some tungsten carbide is removed with brittle fracture, then micro defects are generated on the milled surface. Tool tip shape of the worn PCD tool is copied to the milled groove and makes it a reverse cone-shape.

A Review of the Precision Glass Molding of Chalcogenide Glass (ChG) for Infrared Optics.

Chalcogenide glass (ChG) is increasingly demanded in infrared optical systems owing to its excellent infrared optical properties. ChG infrared optics including ChG aspherical and freeform optics are mainly fabricated using the single point diamond turning (SPDT) technique, which is characterized by high cost and low efficiency. This paper presents an overview of the ChG infrared optics fabrication technique through precision glass molding (PGM). It introduces the thermo-mechanical properties of ChG and models the elastic-viscoplasticity constitutive of ChG. The forming accuracy and surface defects of the formed ChG are discussed, and the countermeasures to improve the optics quality are also reviewed. Moreover, the latest advancements in ChG precision molding are detailed, including the aspherical lens molding process, the ChG freeform optics molding process, and some new improvements in PGM.

Fabricating Microstructures on Glass for Microfluidic Chips by Glass Molding Process.

Compared with polymer-based biochips, such as polydimethylsiloxane (PDMS), glass based chips have drawn much attention due to their high transparency, chemical stability, and good biocompatibility. This paper investigated the glass molding process (GMP) for fabricating microstructures of microfluidic chips. The glass material was D-ZK3. Firstly, a mold with protrusion microstructure was prepared and used to fabricate grooves to evaluate the GMP performance in terms of roughness and height. Next, the molds for fabricating three typical microfluidic chips, for example, diffusion mixer chip, flow focusing chip, and cell counting chip, were prepared and used to mold microfluidic chips. The analysis of mold wear was then conducted by the comparison of mold morphology, before and after the GMP, which indicated that the mold was suitable for GMP. Finally, in order to verify the performance of the molded chips by the GMP, a mixed microfluidic chip was chosen to conduct an actual liquid filling experiment. The study indicated that the fabricating microstructure of glass microfluidic chip could be finished in 12 min with good surface quality, thus, providing a promising method for achieving mass production of glass microfluidic chips in the future.

Ultra-precision finishing of optical mold by magnetorheological polishing using a cylindrical permanent magnet

A magnetorheological polishing was proposed to be used for optical glass mold finishing, aiming at suppressing middle spatial frequency errors from ultra-precision grinding while improving surface roughness. A small polishing head, with a cylindrical permanent magnet enveloped by a nonmagnetic outer shell, was also developed. Polishing experiments were performed on concave aspheric tungsten carbide molds. The results demonstrated the developed magnetorheological polishing successfully suppressed the middle spatial frequency errors on the optical mold by decreasing amplitude to 1 nm, while improving overall surface finish to 1 nm in Ra.

Bonding Characteristics and Chemical Inertness of Zr–Si–N Coatings with a High Si Content in Glass Molding

High-Si-content transition metal nitride coatings, which exhibited an X-ray amorphous phase, were proposed as protective coatings on glass molding dies. In a previous study, the Zr–Si–N coatings with Si contents of 24–30 at.% exhibited the hardness of Si3N4, which was higher than those of the middle-Si-content (19 at.%) coatings. In this study, the bonding characteristics of the constituent elements of Zr–Si–N coatings were evaluated through X-ray photoelectron spectroscopy. Results indicated that the Zr 3d5/2 levels were 179.14–180.22 and 180.75–181.61 eV for the Zr–N bonds in ZrN and Zr3N4 compounds, respectively. Moreover, the percentage of Zr–N bond in the Zr3N4 compound increased with increasing Si content in the Zr–Si–N coatings. The Zr–N bond of Zr3N4 dominated when the Si content was &gt;24 at.%. Therefore, high Si content can stabilize the Zr–N compound in the M3N4 bonding structure. Furthermore, the thermal stability and chemical inertness of Zr–Si–N coatings were evaluated by conducting thermal cycle annealing at 270 °C and 600 °C in a 15-ppm O2–N2 atmosphere. The results indicated that a Zr22Si29N49/Ti/WC assembly was suitable as a protective coating against SiO2–B2O3–BaO-based glass for 450 thermal cycles.