CPI GLASS AND CERAMICS

What is glass in the common sense?

A hard, brittle, transparent amorphous solid used for windows, bottles, or eyewear.

How is glass defined in a technical sense?

An inorganic product of fusion that has been cooled to a rigid condition without crystallizing.

What is the scientific definition of glass?

The term extends to all amorphous solids, including plastics and resins.

What is the origin of the term 'glass'?

It developed in the late Roman Empire, originating from the term 'glesum' in Trier, Germany.

What unique property does glass exhibit at room temperature?

It behaves more like a liquid due to its high viscosity, despite appearing solid.

What happens to glass when it is heated?

It gradually becomes softer and more like a liquid, allowing it to be shaped.

What are the typical states of glass?

Glass exists in a vitreous state with disordered molecular arrangement and mechanical rigidity.

Why is glass useful in modern life?

Due to its transparency, high resistance to chemical attack, effectiveness as an electrical insulator, and ability to contain a vacuum.

What is fused silica?

A type of glass produced by fusing sand at high temperatures, suitable for laboratory apparatus.

What are alkali silicates?

A two-component glass made by melting sand and soda ash, used in various applications.

What is soda-lime glass commonly used for?

It is used to make bottles, tableware, lamp bulbs, and window glass.

What is lead glass known for?

It is heavy, has a high refractive index, and is suitable for lenses, prisms, and decorative objects.

What is the significance of lead oxide in lead glass?

It enhances brilliance and refraction, making it popular for decorative glassware.

What is borosilicate glass used for?

It is known for its durability and is widely used in cooking utensils and laboratory glassware.

What are glass fibers?

Fibers produced from special glass compositions that are resistant to weather conditions.

What is the melting point of fused silica?

About 1700°C.

What is the composition of soda-lime glass?

Typically consists of 75% silica (SiO2) and 25% sodium oxide (Na2O).

What is water glass?

A water-soluble glass produced from soda-lime glass composition.

What is the minimum lead oxide content for glass to be classified as lead crystal?

At least 24% lead oxide (PbO).

What is the trade name for borosilicate glass used in cookware?

Pyrex.

What is the primary use of lead glass in nuclear installations?

As shields to protect personnel from high-energy radiation.

How does glass behave when cooled?

It is cooled to a rigid state without crystallization.

What are the optical properties of glass?

Glass is usually transparent, but can also be translucent or opaque depending on the batch ingredients.

What is the significance of the high index of refraction in lead glass?

It contributes to the glass's sparkling appearance and is important in optical work.

What is the effect of impurities like iron(II) oxide in ordinary soda-lime glass?

It can produce a green tint in thicker pieces.

What are glass fibers produced from?

Special glass compositions that are resistant to weather conditions.

What makes glass fibers vulnerable?

Their very large surface area makes them susceptible to moisture in the air.

What are some applications of glass fiber?

Roof insulation, medical equipment, and woven textile fabrics.

How can glass fibers be produced?

By drawing out molten glass to diameters of a few ten-thousandths of an inch.

What properties make glass fibers suitable for drapery and upholstery?

Chemical stability, strength, and resistance to fire and water.

What is composite fiberglass?

A material formed by impregnating glass fibers with plastics, combining the strength of glass with the impact resistance of plastic.

What is optical glass used for?

Scientific instruments, microscopes, fighter aircraft, and spectacles.

What are the key properties of optical glass?

Refractive index and dispersion, which determine how it bends and splits light.

What is photosensitive glass?

Glass that responds to light, similar to photographic film, used in printing and reproducing processes.

What is photochromic glass?

Glass that darkens when exposed to light and returns to clear when the light is removed.

Where is photochromic glass commonly used?

In spectacle lenses that darken in sunlight and in electronics.

What are glass ceramics?

Materials formed from glass that crystallize under ultraviolet radiation, offering mechanical strength and electrical insulation.

What is the significance of lithium aluminosilicate glass?

It forms glass ceramics that are resistant to thermal shock, used in cookware and missile nose cones.

What are fluxes in glass manufacturing?

Compounds that lower the melting point of sand and promote fusion.

What role do stabilizers play in glass manufacturing?

They are compounds added to increase the durability of the glass.

What is the initial step in glass manufacturing?

Mixing and melting raw materials in large tank furnaces.

What is the casting method in glass shaping?

Pouring molten glass into a mold and allowing it to cool and solidify.

What is glassblowing?

A method where molten glass is insufflated and expanded into various shapes.

How is glass pressed into shape?

By dropping a gather of glass into a mold and using a plunger to form the final shape.

What is the drawing method in glass manufacturing?

Drawing molten glass to create uniform tubing, sheets, fibers, and rods.

What is the rolling method in glass production?

Smoothing molten glass on a flat surface with a roller to produce sheet glass.

How is tubing made in glass manufacturing?

By drawing out a cylindrical mass of semifluid glass while blowing a jet of air down the center.

What is the process of rolling in glass production?

Sheet glass is produced by pouring molten glass on a flat surface and smoothing it with rollers.

What is annealing in glass manufacturing?

A process where glass objects are reheated in an oven called a lehr to relieve internal stresses and then slowly cooled.

What are the steps involved in cutting glass?

Marking the pattern, rough cutting, smoothing, and polishing to produce facets, grooves, and depressions.

How is engraving done on glass?

By using a diamond point or metal needle, or with rotating copper wheels.

What is the etching process in glass finishing?

Achieved with acid, resulting in a decoration that varies from rough to mat finish.

What is sandblasting in glass finishing?

A process where fine grains of sand or powdered materials are projected at high speed onto glass, leaving a mat finish design.

What is cold painting in glass decoration?

Applying lacquer colors or oil paints to glass without firing to affix them.

What is enamel painting in glass finishing?

Painting with enamel colors that are then fused onto the glass surface in a low-temperature firing.

What is gilding in glass decoration?

Applying gold leaf, paint, or dust to glassware, sometimes requiring low-temperature firing for permanence.

What is the origin of the ceramic industry?

It originated in Egypt and Mesopotamia, with significant development during the Chou and Han Dynasties in China.

What are the characteristics of ceramic products?

They can withstand high temperatures, resist pressures, have superior mechanical properties, possess special electrical characteristics, and protect against corrosive chemicals.

What are whitewares in ceramics?

Ceramic products that are usually white and fine-textured, made from selected grades of clay and heated in a kiln.

What is earthenware?

A type of whiteware that is porous and non-translucent, often with a soft glaze.

What distinguishes chinaware from other ceramics?

It is a vitrified translucent ware with a medium glaze that resists abrasion.

What is porcelain?

A vitrified translucent ware with a hard glaze that resists abrasion to the maximum degree, used in various applications.

What is sanitary ware in ceramics?

Previously made from clay, now usually made from vitreous composition for better hygiene.

What is stoneware?

An older ceramic ware regarded as crude porcelain, made from lower-grade raw materials.

What are structural clay products?

Building materials like bricks and tiles made from common clays, often without glazing.

What are refractories?

Materials with high resistance to thermal, physical, and chemical effects, suitable for furnace construction.

What are the three main raw materials in ceramic products?

Clay, feldspar, and sand.

What is clay in ceramics?

An earthly aggregate of hydrous silicates of alumina that is plastic when wet, rigid when dry, and vitreous when fired.

What are the common types of feldspar used in ceramics?

Potash feldspar, soda feldspar, and lime feldspar.

What is the role of sand in ceramic products?

A refractory constituent that must contain low iron for light-colored ceramics.

What are fluxing agents in ceramics?

Additives that facilitate melting and lower the melting points of mixtures.

What is the temperature range for drying in chemical conversions?

20 - 150°C

What process involves the removal of chemically combined water at temperatures of 600 - 650°C?

Dehydration or chemical smoking

What is calcination and its temperature range?

Calcination is a process that occurs at 600 - 900°C.

At what temperature does the oxidation of ferrous iron and organic matter occur?

350 - 900°C

What transformation occurs at 940°C involving alumina?

Amorphous alumina is transferred to crystalline alumina.

What temperature is required for silicate formation?

900 or 1000°C and above

What is the chemical reaction for the dehydration of clay?

Al2O3.2SiO2.2H2O → Al2O3 + SiO2 + 2H2O (600-650°C)

What is formed at 1000°C from kaolinite?

Mullite

What are the two important components of a ceramic body?

A vitreous matrix and crystals, including mullite and cristobalite.

What is the first step in the manufacturing procedure of ceramics?

Storing raw materials without foreign materials or impurities.

What is the purpose of deflocculants in the batching process?

To allow uniform settling irrespective of particle size and to control fluidity.

What is the creamy mixture of raw materials called in ceramics?

Slip

What is the purpose of screening in the manufacturing process?

To remove bits of wood, metal, and other impurities from the slip.

What is the role of magnetic separation in ceramic manufacturing?

To remove iron particles that may stain the fired ware.

What is the slip storage process designed to ensure?

Uniform composition of the slip through continuous stirring.

What is the slip casting method?

A method where slip is poured into dry plaster molds to create products.

What is the final water content of the cake formed in the press method?

18% to 25% after water removal.

What is the purpose of aging in the jiggering method?

To ensure uniform water distribution and develop maximum plasticity.

What is the purpose of de-airing in the jiggering method?

To remove entrapped and absorbed air from the kneaded cake.

What are the finishing steps in ceramic manufacturing?

Trimming, burnishing, wet and dry finishing, and repairing defects.

What is the purpose of glazing in ceramics?

To increase durability, enhance beauty, and improve sanitation of the product.

What are the methods of glazing?

Brushing, dipping, pouring, spraying, vapor glazing, and salt glazing.

What is crawling or creeping in glazing defects?

When glaze forms into beads.

What causes crazing in glazes?

Fine cracks due to a high coefficient of expansion of the glaze.

What is the effect of iron oxide in glazes?

It produces yellow to brownish red colors.

What color does cobalt oxide produce in glazes?

Various shades of blue, violet, or black.

What is the significance of the final drying step in ceramic manufacturing?

To increase kiln efficiency and minimize defects due to moisture.

What is the purpose of underglazed decorations?

To apply colors and decorations before glazing and firing.