345 results about "Flat glass" patented technology

The invention provides a projection lens, which sequentially comprises a first lens with positive focal power from a projection surface to an image source surface along an optical axis, a second lens with negative focal power and a third lens with positive focal power from the projection surface to the image source surface, the surface of the projection side of the second lens is a convex surface, and the surface of the image source side of the second lens is a concave surface; the surface of the projection side of the third lens is a concave surface, and the surface of the image source side of the third lens is a concave surface; the surface of the projection side of the fourth lens is a convex surface, and the surface of the image source side of the fourth lens is a convex surface; the surface of the image source side of the fifth lens is a convex surface; the surface of the projection side of the sixth lens is a convex surface; a prism; a protective glass; a piece of plate glass with changeable positions is arranged between the prism and the protective glass, and the plate glass can be located at a first position or a second position through a switching device. According to the projection lens provided by the invention, clear imaging at two different projection distances is realized through switching of the plate glass, and switching between a close shot and a long shot is completed.

The invention provides a projection lens, which sequentially comprises a first lens with positive focal power from a projection surface to an image source surface along an optical axis, a second lens with negative focal power and a third lens with positive focal power from the projection surface to the image source surface, the surface of the projection side of the second lens is a convex surface, and the surface of the image source side of the second lens is a concave surface; the surface of the projection side of the third lens is a concave surface, and the surface of the image source side of the third lens is a convex surface; the surface of the projection side of the fourth lens is a concave surface; the surface of the projection side of the fifth lens is a concave surface, and the surface of the image source side of the fifth lens is a convex surface; the surface of the projection side of the sixth lens is a convex surface, and the surface of the image source side of the sixth lens is a convex surface; a prism; a protective glass; plate glass is arranged between the prism and the protective glass, and the plate glass can be located at a first position or a second position through a switching device. According to the projection lens provided by the invention, clear imaging at two different projection distances is realized through switching of the plate glass, and switching between a close shot and a long shot is completed.

The invention provides a vernier effect-based micro-ring resonant cavity acoustic sensor, and belongs to the technical field of optical-acoustic sensors. Comprising a coupling unit; the light source is used for generating light signals; the cascade sensing ring unit comprises a front-stage sensing ring and a rear-stage reference ring, one end of the front-stage sensing ring is connected with a light path of the light source, and the other end of the front-stage sensing ring is connected with a light path of one end of the rear-stage reference ring through the coupling unit; wherein each of the front-stage sensing ring and the rear-stage reference ring comprises a hollow plate glass substrate, a first PDMS thin film, a micro-nano optical fiber knot and a second PDMS thin film which are sequentially stacked, and the two ends of the micro-nano optical fiber knot in the axial extension direction serve as the two ends of the sensing ring; the radius and the free spectral range of the micro-nano optical fiber junctions of the front-stage sensing ring and the rear-stage reference ring are different. The micro-nano optical fiber knot and the multi-stage sensing ring structure are adopted, the acoustic sensor can accurately detect weak acoustic pressure change, and the sensing ring is very sensitive to wavelength drift and acoustic pressure change.

The utility model relates to a special sucking disc for sucking plate glass, which comprises a hollow connecting rod and a sucking disc body forming a negative pressure cavity, a sealing lip edge is arranged at the edge of a disc opening of the sucking disc body, the sealing lip edge is composed of at least three concentric annular sealing lips, and the thickness of each annular sealing lip is gradually reduced towards one side deviating from the sucking disc body; one end of the hollow connecting rod is communicated with the negative pressure chamber of the sucker body, and the other end is connected with an external vacuum generating device; the hollow connecting rod is movably connected with the suction cup body, so that the hollow connecting rod and the suction cup body can rotate relatively. The suction cup special for sucking the plate glass is in contact with the surface of the glass in a linear contact mode, and even if mildew-proof powder or a suction cup sleeve exists, tight attachment can be ensured, vacuum can be rapidly established, and stable suction force can be kept; meanwhile, the hollow connecting rod is movably connected with the suction cup body, so that the suction cup has the capability of automatically adjusting the angle, and the suction cup can adapt to unevenness of the glass surface and inclination in the carrying process.

The utility model relates to the technical field of glass cleaning equipment, in particular to plate glass cleaning equipment, which uses symmetrically arranged cleaning mechanisms to clean two sides of glass at one time and improve the cleaning efficiency, and is provided with two scraping plates to scrape off water stains on the glass and improve the cleaning effect. Comprising a body; the cleaning machine comprises a machine body and further comprises a collecting device, a conveying device, a telescopic device, a linkage mechanism, a clamping device and a cleaning device, the collecting device, the conveying device and the telescopic device are all installed on the machine body, the linkage mechanism is installed on the telescopic device, the clamping device is installed on the linkage mechanism, and the cleaning device is installed on the collecting device and the linkage mechanism; the machine body and the linkage mechanism provide support, the collecting device collects and stores waste water, the conveying device moves glass, the telescopic device enables a gap between the conveying device and the cleaning device to be changed, the machine can adapt to glass of various thicknesses, the clamping device clamps the glass, and the cleaning device cleans the glass.

The invention relates to the technical field of polyamide high polymer materials, in particular to a glass fiber reinforced PA6 composite material and a preparation method thereof. The glass fiber reinforced PA6 composite material comprises the following components in percentage by weight: 20-50% of PA6 resin; 50 wt%-80 wt% of flat glass fibers; 0 wt%-2 wt% of an antioxidant, which is not 0; 0 wt%-1 wt% of a lubricant, which is not 0; 0 wt%-2 wt% of black master batch, which is not 0; the sum of the dosages of the components is 100%. According to the glass fiber reinforced PA6 composite material provided by the invention, only three auxiliary agents are used, the components are simple, the components can be well matched in a specific ratio range, and the obtained glass fiber reinforced PA6 composite material has high glass fiber content, good melt processing characteristics, excellent comprehensive mechanical properties, good barrier property and apparent quality, and can be widely applied to the field of glass fiber reinforced plastic. And the forming processing method is simple.

The invention discloses a high-strength low-warpage POK composite material, a preparation method thereof and a plastic part, and the high-strength low-warpage POK composite material provided by the invention is prepared from the following raw material components in parts by weight: 40 to 60 parts of POK resin, 10 to 15 parts of mineral filler, 30 to 40 parts of glass fiber, 0.1 to 0.3 part of antioxidant and 0.2 to 0.5 part of lubricant. The glass fibers are at least one of flat glass fibers and ground glass fibers. In a POK material system, specific types of glass fibers and mineral filler are added, and the combination ratio of the glass fibers to the mineral filler is adjusted, so that the comprehensive performance and warping resistance of the POK are greatly improved on the basis of not damaging the original wear resistance, chemical resistance and hydrolysis resistance of the POK.

The invention discloses a continuous type hollow glass brick surface paint spraying system and technology, relates to the technical field of spray coating, and aims to solve the technical problems that an existing mechanical arm is multiple in paint spraying limitation, low in efficiency and prone to mixing during cleaning. The continuous type hollow glass brick surface paint spraying system comprises a water containing plate, a paint spraying mechanism, a universal assembly and a flushing assembly. The straight line gathering or unfolding of the hard pipeline is matched with the up-and-down movement of the limiting plate, when the gun head gathers, paint is vertically sprayed to the flat glass brick, and it is guaranteed that a plane paint layer is even and free of omission; when the gun heads are unfolded, independent multi-direction paint spraying of the multiple gun heads is achieved by means of matching of the outer ball head pipes and the inner ball head pipes, glass bricks with groove patterns are matched, and leakage spraying, thin coating and accumulation of grooves are avoided; the flushing assembly is sealed and matched with a blocking piece through a hollow ball head communicating structure and a blocking piece, and during paint spraying, the blocking piece seals a water inlet to keep paint pure; during cleaning, the blocking piece resets to seal the blocking piece, the water inlet is communicated, cleaning liquid accurately enters the gun head for cleaning and does not need to flow through an external pipeline, and the paint spraying requirements of different glass bricks are met.

The invention relates to the technical field of glass curtain wall installation equipment, and discloses a glass curtain wall auxiliary installation device which comprises an installation frame, two sets of vacuum suction cups are arranged on the side, away from a lifting rod and a vacuum pump, of the installation frame, and the vacuum suction cups and the installation frame are rotationally connected through a rotary supporting device. The rotary supporting device comprises two sets of supporting blocks fixedly arranged on one side of the mounting frame, a telescopic piece is rotationally connected between each set of supporting blocks, and one ends of the two telescopic pieces are fixedly connected with the vacuum suction cup. The rotary supporting devices are arranged between the multiple vacuum suction cups and the mounting frame for rotary connection, the design of telescopic pieces in the rotary supporting devices is matched, a plane glass curtain wall can be adsorbed, the vacuum suction cups can rotate relative to the mounting frame, and therefore all the vacuum suction cups can be controlled to be aligned with and adsorb an arc-shaped glass curtain wall, and the service life of the arc-shaped glass curtain wall is prolonged. And a constructor is assisted to install the arc-shaped glass curtain wall in a corresponding floor.

The present invention relates to a large-aperture and large-image-surface space debris monitoring optical system. The optical system is provided with a front fixed group A with negative optical power, an aperture, and a rear fixed group B with positive optical power in sequence along the incident light path. The front fixed group A is composed of a meniscus positive lens A1, a first cemented group formed by closely bonding a biconvex positive lens A2 and a biconcave negative lens A3, and a second cemented group formed by closely bonding a meniscus positive lens A4 and a meniscus negative lens A5. The rear fixed group B is composed of a biconvex positive lens B1, a biconcave negative lens B2 and a biconvex positive lens B1. The optical system consists of a third cemented group formed by closely bonding lenses B3, a biconvex positive lens B4, a fourth cemented group formed by closely bonding biconvex positive lens B5 and biconcave negative lens B6, a meniscus positive lens B7, a meniscus negative lens B8 and flat glass B9; the optical system has high resolution, low distortion, small chromatic aberration, strong monitoring capability, large aperture and large image surface, which are conducive to enhancing the energy entering the optical system, monitoring smaller space debris, and increasing the monitoring range of space debris; a weight-reduction design is adopted to effectively control the weight of the lenses, which is conducive to the carrying of aircraft.

The invention provides a laser-induced surface metallized glass fiber reinforced polyether-ether-ketone modified material and a preparation method thereof. The laser-induced surface metallized glass fiber reinforced polyether-ether-ketone modified material is prepared from the following components in percentage by weight: 39%-69.5% of PEEK resin, 20%-40% of low-dielectric flat glass fiber, 5%-10% of low-dielectric filler, 5%-10% of Cu-Ni coordination compound and 0.5%-1% of antioxidant. According to the invention, the Cu-Ni coordination compound is added into the PEEK modified material, then the PEEK modified material is subjected to laser induction treatment with a specific wave band, reducing cuprous ions or nickel ions are obtained on the surface layer of the PEEK modified material, and then the reducing cuprous ions or nickel ions are catalytically reduced into metal atoms through an electroplating process, so that the metal layer is embedded into the PEEK base material, and the binding force between the metal coating and the PEEK base material is improved.

1. The name of the design product: the right end of glass steel heat treatment equipment. 2. The use of the design product: used as heating equipment for tempered glass production; the right end is used for inputting ordinary flat glass. 3. The design points of the design product: the shape of the right end of the product. 4. The picture or photo that best shows the design points: perspective view 1. 5. The bottom of the design product is not easily visible or invisible during use, so the top view is omitted; the partial design is not visible on the left side, so the left view is omitted. 6. Other circumstances that need to be explained: the part other than the yellow translucent layer in this application is the partial design that the design application requests protection.

The application discloses light laminated glass for automobile and a preparation method thereof, wherein the light laminated glass for automobile comprises, from inside to outside, a hot-bending thick glass layer, a film layer, a thin flat glass layer and a coating layer. The light laminated glass for automobile comprises, from inside to outside, a hot-bending thick glass layer, a film layer, a thin flat glass layer and a coating layer. The existing hot-bending glass is difficult to control the film thickness and uniformity in the coating and other deep processing process due to the certain curvature, while the thin flat glass is easier to be coated and other deep processed, thereby reducing the technical difficulty in production and the cost. Meanwhile, the light laminated glass for automobile is made of the hot-bending thick glass layer and the thin flat glass layer instead of the traditional two-piece thick hot-bending glass, so that the light weight effect can be achieved, and the method does not need the curvature to be completely consistent, thereby reducing the risk of glass breakage.

The application discloses a kind of functionalization of preparation method of special-shaped glass bottle, belong to glass bottle preparation technical field.It includes the following steps:Step 1: functional film layer is prepared on the surface of flat glass, and coated flat glass is obtained;Step 2: the coated flat glass is formed into bottle body half by hot bending settlement and die pressing compound;Step 3: after the two bottle body halves are finely polished and aligned and fixed, heating fusion is carried out, then flame polishing is carried out, and finally precise annealing is carried out, to obtain the functionalization of special-shaped glass bottle.The application provides a kind of "coating film first, then forming" special-shaped glass bottle preparation method, which effectively solves the problem of uneven coating film on the surface of complex special-shaped bottle in the traditional method, and the problem of poor bonding force.The process difficulty is reduced, and the integrity and firmness of the film layer on the inner surface of the bottle are ensured.

The utility model relates to the field of glass lens molds, and provides a mold for pressing a high borosilicate glass lens, which comprises a punch, an opening ring and a bottom mold, the bottom end of the opening ring is fixedly connected with the bottom die, the punch is arranged in the opening ring, and the driving device drives the punch to press downwards to be pressed with the bottom die to form a pressed flat glass lens. An annular protrusion is arranged on the edge of the bottom end of the punch. A plurality of heat preservation blocks are arranged at the bottom end of the bottom die, and grooves are formed in the middles of the upper surfaces of the heat preservation blocks. The mold has the beneficial effects that the heat preservation effect of molten glass in the mold is obviously improved by arranging the heat preservation block, and the molten glass is prevented from entering a mold closing seam by arranging the annular bulge, so that the generation of glass chips is reduced.

The present invention relates to the technical field of processing and application of special glass and energy-saving doors and windows, and proposes a hollow glass window manufacturing process and hollow glass window, comprising the following steps: S1, improving the surface roughness of the glass and making it into flat glass; S2, placing the flat glass into a heating furnace to soften it; S3, conveying the flat glass into a coolant spray chamber for cooling, and the conveying mechanism drives the flat glass to move along a continuous S-shaped path on a horizontal plane; S4, using an adhesive to bond the flat glass and the connecting frame; S5, installing the two bonded flat glasses into a frame. The present invention allows the flat glass to move along a continuous S-shaped path on a horizontal plane when passing through the coolant spray chamber, which not only allows the flat glass to be evenly cooled, but also accelerates the separation efficiency of the coolant on the upper surface of the flat glass and the flat glass, thereby improving the tempering efficiency of the flat glass and accelerating the processing speed of the hollow glass window.

The invention discloses a novel high-definition 3D (three-dimensional) display device. The invention provides an innovative solution for solving the problems that the development of the current 3D image technology is slow, and various 3D display devices have defects to hinder the popularization of the technology. The two high-definition 2D display screens with the same size are oppositely placed to be in an inward folding and overturning state, and the included angle between the two screens ranges from 0 degree to 180 degrees and can be overturned at will, and the included angle is temporarily 90 degrees. Transparent plate glass which is 50% in reflectivity and transparency and forms an equal included angle with the two display screens is additionally arranged between the two screens, the two screens respectively display 3D image files of a left channel and a right channel, and a user can watch high-definition 3D images by customizing different polarization directions of the screens and wearing corresponding polarized light glasses. The two 2D screens of the equipment respectively display at full frame rate and full resolution in the whole process, do not need to switch left and right channels, have a large visual field, are suitable for being watched by multiple persons, have no flicker and high fidelity, and are suitable for different scenes, and the sizes of the screens can be customized.

This invention relates to the field of polymer materials technology. It discloses a low-linearity polypropylene-talc composite material, its preparation method, and its applications. The material comprises the following raw materials in weight percentages: polypropylene resin: 50-65%, modified talc: 15-25%, ethylene-octene copolymer resin: 10-15%, modified flat glass fiber: 5-15%, basic magnesium sulfate whiskers: 3-10%, heat stabilizer: 0.3-1%, and antioxidant: 0.1-0.5%. This composite material exhibits advantages such as a low coefficient of linear expansion, excellent surface tension, and superior mechanical properties.

This invention relates to a glass cover with an outer frame, wherein a flat glass plate is directly joined to the outer frame, wherein the glass matrix within the outer frame comprises at least one of bismuth oxide and boron oxide, and the glass ceramic has a coefficient of thermal expansion of 15 × 10⁻⁶. －7 In the glass ceramics described above, the total volume fraction of the negative thermal expansion filler and the total volume fraction of the filler components are both 40% to 65%, and the softening point of the glass components in the glass matrix is ​​lower than the glass transition point of the flat glass.

In aerogel glass plates, we provide a water droplet dispersion glass plate that completely eliminates residual water droplets adhering to the glass surface facing the outside air through the lotus effect. [Solution] In the aerogel plate glass 1, a water droplet dispersion plate glass G was formed in which irregularities ranging from several micrometers to more than 10 micrometers were formed on the glass surface 1A of at least one side of the glass by any means such as plasma treatment, nanocoating, or laser microfabrication.

The present invention relates to a fixed-focus lens, which sequentially includes, along the optical axis from the object side to the image side: a first lens with a negative optical power, a second lens with a positive optical power, a diaphragm, a third lens with a positive optical power, a fourth lens with a negative optical power, a fifth lens with a positive optical power, and a protective flat glass. The effective focal length F of the fixed-focus lens and the effective focal length F1 of the first lens satisfy the following relationship: 1.2 ≤ |F1 / F| ≤ 1.5. For the fixed-focus lens of the present invention, by reasonably setting the concavity and convexity, material, and optical power distribution of each lens, it can better collect and transmit light, helps to obtain a larger field of view angle, effectively corrects visible light, infrared, and high and low temperature aberrations. Under the requirement of better light transmissibility, the miniaturization and low cost of the fixed-focus lens are realized. Under the requirement of high performance, it can achieve no defocus within the temperature range of -40°C to 70°C and day-night confocal, so as to be applicable to various environments.

A method for melting vitrifiable materials to produce flat glass, including: providing a furnace including: a melting tank, a fining tank, a neck, at least one inlet means located at the melting tank, an outlet means located downstream of the fining tank, and at least one extraction means of a flue gas located at the at least one upstream zone; charging the vitrifiable materials including raw materials and cullet in the melting tank with the at least one inlet means; cullet pre-heating; melting the vitrifiable materials in the melting tank; fining the melt in the fining tank; flowing the melt from the fining tank to a working zone through the outlet means; and capturing CO2 from the flue gas.

The invention provides a differential photoacoustic gas sensing system and method based on cross-correlation demodulation, and is suitable for the fields of trace gas monitoring, industrial process fine control and environment detection. The system comprises a gas excitation light source, a symmetrical double-probe gas sensor, an optical fiber circulator, a wide-spectrum light source, a 1 * 2 optical fiber coupler, two pieces of plain glass, a photoelectric detection array and a computer, acoustic wave signals excited by the photoacoustic effect generate difference superposition cavity length changes on the symmetrically-arranged double cantilever beams, and environment noise triggers cavity length responses which are counteracted in the same direction. The system adopts an optical cross-correlation demodulation algorithm to track peak displacement of a cross-correlation function in real time, dynamically demodulates cavity length change information, and inverts the gas concentration according to the information. According to the design scheme, effective photoacoustic signals are remarkably enhanced, meanwhile, effective suppression of environment vibration noise is achieved, and finally the trace gas detection system integrating the advantages of miniaturization, high sensitivity and low cost is constructed.

The refrigerator plate glass processing equipment with the positioning function comprises a bottom plate, fixing plates are welded to the two sides of the upper end of the bottom plate, connecting rods are arranged between the two fixing plates, and the two connecting rods are of a front-back symmetrical structure; an adjusting device of a penetrating structure is installed between the two fixing plates, a first limiting frame of a penetrating structure is installed on the adjusting device, and a second limiting frame of a symmetrical structure is arranged on the left side of the first limiting frame. The adjusting device is arranged between the two fixing plates, the motor is controlled, the motor drives the threaded rod to rotate, the distance between the two limiting frames is adjusted so as to adapt to the width of glass, the fixing device of a rotating structure is arranged at the upper ends of the two limiting frames, rotation can be conducted according to the machining position of the glass, and the machining precision of the glass is improved. Furthermore, the glass is fixed through the positioning block by controlling the control rod, so that the processing range of the glass is enlarged.

The invention discloses an O-shaped ring quick-changing structure of a driving unit of an inclined carrying device and a positioning method, and belongs to the technical field of plate glass manufacturing equipment. Comprising a driving shaft and an O-shaped ring mounting seat which are coaxially arranged, a driving shaft convex conical surface is arranged at the end part of the driving shaft; a concave conical surface is arranged at the butt joint end of the O-shaped ring mounting seat; the concave conical surface is in surface contact fit with the convex conical surface of the driving shaft to form a conical surface self-positioning system for realizing automatic centering between the driving shaft and the O-shaped ring mounting seat; a positioning piece used for limiting relative displacement in the rotating direction is arranged at the conical surface matching position of the concave conical surface and the convex conical surface; a magnetic anti-loosening disc is arranged at the end of the driving shaft, radial pre-tightening is generated on the matched conical surface through magnetic force, and a positioning and locking system linked with the positioning piece is formed. Through the synergistic effect of self-positioning of the conical surface, rotation prevention of the positioning pin and magnetic locking, the replacement time of the O-shaped ring is shortened from 15 min to 1 min, the positioning precision is improved to + / -0.02 mm, and breakthrough improvement of maintenance efficiency and equipment reliability is achieved.

This utility model relates to the technical field of glass processing edging equipment, and discloses a glass processing edging machine, including a machine body and a worktable mounted on the machine body. A glass positioning mechanism and a glass edging mechanism are sequentially arranged on the worktable. The worktable also includes a glass fixing mechanism for fixing the glass. Driven by a moving drive mechanism, the glass fixing mechanism moves the glass from the glass positioning mechanism to the glass edging mechanism for edging processing. This utility model can automatically adjust the distance between the grinding roller and the glass side, reducing labor intensity and improving grinding efficiency. Simultaneously, during the grinding process, multiple grinding wheels perform progressively fine grinding, resulting in smooth and flat glass sides. This avoids situations where a single grinding wheel's grinding volume is too large, leading to poor grinding results or glass breakage, greatly improving grinding efficiency and finished product quality. It also reduces material waste and manual intervention, ensuring the stability and reliability of the production process.

Described herein are polymer compositions including at least 20 wt. % of a liquid crystal polymer (“LCP”); 10 wt. % to 40 wt. % of a flat glass fiber and 15 wt. % to 50 wt. % of boron nitride and / or zinc oxide. It was surprisingly discovered that polymer compositions including an LCP in conjunction with a combination of flat glass fibers and boron nitride and / or zinc oxide had improved thermal conductivity and flexural properties, relative to analogous polymer compositions having round glass fibers in place of the flat glass fibers.

The utility model relates to the field of glass detection, in particular to a stripe detection device for plate glass, which comprises a light source, a placing frame and a horizontal rotary table, the light source is opposite to the front surface of the plate glass, the placing frame comprises a horizontal rotary frame and a vertical rotary frame, and the plate glass is fixed on the vertical rotary frame. The vertical rotating frame is rotationally connected to the horizontal rotating frame, the horizontal rotating frame comprises a rotating shaft, and the horizontal rotating table is rotationally connected with the horizontal rotating frame through the rotating shaft. The plate glass can be stably placed through the arrangement of the placing frame, optical detection can be carried out on the plate glass at all angles under the condition that the light source is not repeatedly moved through rotation of the horizontal rotary table and the vertical rotary frame, and the accuracy and reliability of stripe detection are improved.

This invention relates to the field of microcrystalline glass technology, and discloses a high-toughness, anti-glare sodium-calcium nanocrystalline glass, its preparation method, and its application. The nanocrystalline glass is composed of glass raw materials, nucleating agents, and crystallizing agents. The preparation method is as follows: (1) grinding and mixing the glass raw materials in proportion to obtain a mixture; (2) heating the mixture to melt to obtain a glass melt; (3) pouring the glass melt into a preheated mold for molding, and then annealing it to obtain a base glass; (4) adding nucleating agents and crystallizing agents to the base glass; (5) performing a one-step heat treatment on the base glass to obtain sodium-calcium nanocrystalline glass; (6) performing a surface coating treatment on the sodium-calcium nanocrystalline glass to obtain a high-toughness, anti-glare sodium-calcium nanocrystalline glass. The microcrystalline glass prepared by this invention has a dense structure, high toughness, and high anti-glare characteristics, and can be used as a microcrystalline glass material for mobile phone and tablet glass covers.

The present invention relates to a composition for glass articles, in particular for flat glass, glass packaging and household glass products. The glass composition of the invention has been developed within the SiO2-AI2O3-CaO-MgO-Na2O system and has superior mechanical and chemical durability. The composition comprises, in weight percent, 55-70 SiO2, 5-15 AI2O3, 5-15 MgO, 0-8 CaO, 5-18 Na2O and 0-4 B2O3.