What are the primary constituents of borosilicate glass?

Borosilicate glass is primarily composed of silica and boron trioxide, which serve as the main glass-forming agents. These components give the glass its distinctive properties.

What is a defining characteristic of borosilicate glass regarding its response to temperature changes?

Borosilicate glass is known for having very low coefficients of thermal expansion. This property means that the glass expands and contracts very little when subjected to temperature changes.

How does the low coefficient of thermal expansion contribute to borosilicate glass's durability?

Due to its low coefficient of thermal expansion, borosilicate glass experiences less internal thermal stress when temperature gradients occur. This makes it significantly more resistant to thermal shock compared to other common types of glass.

What is the approximate temperature differential that borosilicate glass can withstand without fracturing?

Borosilicate glass can typically withstand temperature differentials of about 330 degrees Fahrenheit (166 degrees Celsius) without fracturing. This high tolerance for temperature changes is a key advantage in many applications.

What are some common applications for borosilicate glass mentioned in the introductory section?

Borosilicate glass is commonly used in the construction of laboratory equipment such as reagent bottles and flasks. It is also found in lighting, electronics, and cookware.

How does the prevalence of borosilicate glass compare to soda-lime glass for general applications?

While borosilicate glass is used for many specialized applications, soda-lime glass is more commonly used for a wider range of everyday items. Borosilicate glass is chosen when its specific properties, like thermal shock resistance, are required.

What is the approximate coefficient of thermal expansion for borosilicate glass at 20°C?

The coefficient of thermal expansion for borosilicate glass is approximately 3 x 10⁻⁶ K⁻¹ at 20°C. This very low value is central to its thermal shock resistance.

How is borosilicate glass utilized in certain types of lamps?

Borosilicate glass serves as the material for the gas discharge tube (arc tube) in single-ended self-starting lamps. These lamps are often insulated with a mica disc and enclosed in a metal cap, with sodium-vapor lamps used in street lighting being a notable example.

At what approximate temperature does borosilicate glass typically melt?

Borosilicate glass generally melts at around 1,650 degrees Celsius (3,000 degrees Fahrenheit).

Who is credited with the initial development of borosilicate glass, and where did this occur?

Borosilicate glass was first developed by the German glassmaker Otto Schott in the late 19th century in Jena, Germany. This early type of glass became known as Jena glass.

What significant event marked the introduction of Pyrex, and how did it impact the perception of borosilicate glass?

Corning Glass Works introduced Pyrex in 1915. The name Pyrex subsequently became synonymous with borosilicate glass in English-speaking regions, although the brand has also used soda-lime glass for some products since the 1940s.

What are the main ingredients melted together to produce borosilicate glass?

The manufacturing of borosilicate glass involves melting boric oxide, silica sand, soda ash, and alumina together. These components form the basis of its unique chemical and physical properties.

What manufacturing challenges did borosilicate glass present compared to traditional silicate glass?

Because borosilicate glass melts at a higher temperature than ordinary silicate glass, new industrial production techniques were required to handle its manufacturing. This higher melting point is a direct result of its specific chemical composition.

Beyond silica, what other key element is essential in the composition of borosilicate glass?

In addition to traditional glassmaking components like silica, sodium carbonate, and aluminum oxide, boron is the essential element used in the manufacture of borosilicate glass.

What is the approximate chemical composition of common low-expansion borosilicate glass?

Low-expansion borosilicate glass typically consists of approximately 80% silica, 13% boric oxide, 4% sodium oxide or potassium oxide, and 2-3% aluminum oxide. This precise formulation contributes to its desirable properties.

Despite being more difficult to produce, why is borosilicate glass considered economical?

Although borosilicate glass has a higher melting temperature, making it more challenging to produce than traditional glass, it is considered economical due to its superior durability, chemical resistance, and heat resistance, which lead to longer product life and reduced replacement costs in many applications.

What manufacturing methods are employed for borosilicate glass, varying by product shape?

The manufacturing process for borosilicate glass can utilize different methods such as floating, tube drawing, or molding, depending on the specific geometry and intended use of the final product.

How does the thermal expansion coefficient of borosilicate glass used in laboratory glassware compare to soda-lime glass?

The common type of borosilicate glass used for laboratory glassware has a thermal expansion coefficient of 3.3 x 10⁻⁶ K⁻¹, which is about one-third that of ordinary soda-lime glass. This significantly lower expansion reduces stress within the material.

While superior to other glasses, what can still cause borosilicate glass to fracture?

Despite its enhanced resistance to thermal shock, borosilicate glass can still crack or shatter if subjected to rapid or uneven temperature variations. Proper handling and gradual temperature changes are still important.

How does borosilicate glass facilitate direct seals with metals like molybdenum, tungsten, and Kovar?

Borosilicate glasses offer a range of thermal expansion coefficients that can be matched to specific metals and alloys. For instance, certain borosilicate compositions have coefficients that closely align with those of molybdenum (4.6 x 10⁻⁶ K⁻¹), tungsten (around 4.0 x 10⁻⁶ K⁻¹), and Kovar (around 5.0 x 10⁻⁶ K⁻¹), enabling strong, direct seals.

What is the typical maximum operating temperature for borosilicate glass?

Borosilicate glass can generally withstand high temperatures, typically up to about 500 degrees Celsius (930 degrees Fahrenheit) for continuous use.

How does borosilicate glass perform in chemically corrosive environments?

Borosilicate glass exhibits extremely high chemical resistance, even under the harsh conditions created by standard tests for acid resistance, showing minimal impact from corrosive substances.

What is the softening point of type 7740 Pyrex glass?

The softening point, the temperature at which its viscosity reaches approximately 10⁷.⁶ poise, for type 7740 Pyrex is 820 degrees Celsius (1,510 degrees Fahrenheit).

How does the density of borosilicate glass compare to soda-lime glass, and what is the reason for this difference?

Borosilicate glass is less dense, approximately 2.23 g/cm³, than typical soda-lime glass. This lower density is attributed to the lower atomic mass of boron compared to the elements more prevalent in soda-lime glass.

What is the approximate mean specific heat capacity of borosilicate glass?

The mean specific heat capacity of borosilicate glass at constant pressure, measured between 20-100°C, is about 0.83 J/(g·K). This value is roughly one-fifth that of water.

What is the practical difference in thermal shock resistance between borosilicate glass and soda-lime glass?

Borosilicate glass can withstand a temperature change of about 330°F (170°C), whereas soda-lime glass can only handle about 100°F (40°C). This means kitchenware made of traditional soda-lime glass might shatter if a hot vessel is placed on an icy surface, while borosilicate glass is much less likely to.

What are the optical properties of borosilicate glasses regarding dispersion and refractive index?

Optically, borosilicate glasses are classified as crown glasses. They exhibit low dispersion, with Abbe numbers around 65, and relatively low refractive indices, typically ranging from 1.51 to 1.54 across the visible light spectrum.

In the context of molten glass, what does 'fragility' refer to, and how does boron content influence it?

In molten glass, 'fragility' refers to how rapidly the viscosity changes with temperature. Molten borosilicates tend to be more fragile than silicates, meaning their viscosity changes more drastically with temperature fluctuations. The fragility index generally increases as the boron content increases.

What structural changes occur in molten borosilicate glass as it heats up?

As molten borosilicate glass heats up, structural changes occur, including the reversible depolymerization of the glass network. The boron atoms also change their coordination environment, shifting from a tetrahedral structure at lower temperatures to a trigonal planar structure at higher temperatures.

What are the defining chemical characteristics of the 'Non-alkaline-earth' family of borosilicate glasses?

Non-alkaline-earth borosilicate glasses typically contain about 12-13% boric oxide (B₂O₃) and over 80% silica (SiO₂). They are characterized by high chemical durability and the lowest thermal expansion among commercial glasses used in large-scale technical applications.

What are some typical applications for 'Non-alkaline-earth' borosilicate glasses?

High-grade borosilicate flat glasses from the non-alkaline-earth family are used in various industries, particularly for technical applications requiring good thermal resistance, excellent chemical durability, or high light transmission with a pristine surface. They are also used for glass tubing, piping, and containers, especially within the chemical industry.

What distinguishes 'Alkaline-earth' borosilicate glasses from other types?

'Alkaline-earth' borosilicate glasses contain approximately 75% SiO₂ and 8-12% B₂O₃, along with up to 5% oxides from alkaline earth metals and alumina. They are slightly softer than non-alkaline-earth types and have thermal expansion coefficients in the range of 4.0-5.0 x 10⁻⁶ K⁻¹.

What are the key features of 'High-borate' borosilicate glasses?

'High-borate' glasses contain a higher percentage of boric oxide (15-25%) and less silica (65-70%), with smaller amounts of alkalis and Al₂O₃. Their main advantages are low softening points, low thermal expansion, sealability to metals like tungsten and molybdenum, and high electrical insulation properties.

How does the high boric oxide content in 'High-borate' glasses affect their chemical resistance?

The increased boric oxide content in 'High-borate' borosilicate glasses leads to a reduction in their chemical resistance. This makes them differ significantly in chemical durability compared to non-alkaline-earth and alkaline-earth borosilicate glasses.

What unique optical capability do some 'High-borate' borosilicate glasses offer?

Certain 'High-borate' borosilicate glasses can transmit ultraviolet (UV) light down to wavelengths as low as 180 nm. This property combines the benefits of borosilicate glass with some of the UV transmission characteristics of quartz.

Why is borosilicate glass the standard material for modern laboratory glassware?

Virtually all modern laboratory glassware is made from borosilicate glass due to its excellent chemical and thermal resistance, as well as its good optical clarity. These properties ensure reliability and safety in demanding laboratory environments.

Under what specific conditions can borosilicate glass react with sodium hydride, and what is the product?

Borosilicate glass can react with sodium hydride when heated, producing sodium borohydride. Sodium borohydride is a commonly used reducing agent in laboratory chemistry.

When is fused quartz preferred over borosilicate glass in laboratory settings, and why is it less common?

Fused quartz is preferred over borosilicate glass for specific laboratory equipment when its higher melting point and superior transmission of UV light are required, such as for tube furnace liners or UV cuvettes. However, the higher cost and manufacturing difficulties associated with fused quartz make it impractical for the majority of laboratory glassware.

How is borosilicate glass tubing utilized in the pharmaceutical industry?

Borosilicate glass tubing serves as the primary material for producing parenteral drug packaging, including vials, pre-filled syringes, ampoules, and dental cartridges. Its chemical inertness is crucial for maintaining drug stability.

What makes borosilicate glass particularly suitable for injectable drug applications?

The high chemical resistance of borosilicate glass minimizes the leaching of sodium ions from the glass matrix into the contents. This stability is essential for pharmaceutical applications, especially for injectable drugs where purity is paramount.

What classification is typically given to borosilicate glass used for pharmaceutical packaging?

Borosilicate glass used for pharmaceutical packaging, such as vials and syringes, is typically referred to as USP / EP JP Type I glass. This designation indicates its compliance with stringent pharmaceutical standards.

In which types of implantable medical devices is borosilicate glass commonly incorporated?

Borosilicate glass is widely used in various implantable medical devices, including prosthetic eyes, artificial hip joints, bone cements, and dental composite materials (used for fillings).

What are some examples of implantable devices that benefit from borosilicate glass encapsulation?

Several implantable devices benefit from the protective qualities of borosilicate glass encapsulation. These include veterinary tracking devices, neurostimulators for epilepsy treatment, implantable drug pumps, cochlear implants, and physiological sensors.

How was borosilicate glass tubing used in mid-20th century electronics?

During the mid-20th century, borosilicate glass tubing was employed to channel coolants, often distilled water, through high-power vacuum-tube-based electronic equipment, such as commercial broadcast transmitters. It was also used as the envelope material for glass transmitting tubes that operated at high temperatures.

What role does borosilicate glass play in the semiconductor industry for MEMS development?

In the semiconductor industry, borosilicate glass is used in the development of microelectromechanical systems (MEMS). It is often incorporated into stacks of etched silicon wafers that are bonded to etched borosilicate glass components.

What are common uses for borosilicate glass in cookware?

Borosilicate glass is frequently used for cookware, including bakeware and measuring cups that feature printed graduated measurements. It is also sometimes used for high-quality beverage glassware, especially for hot drinks.

What features make borosilicate glass cookware suitable for modern kitchen appliances?

Items made from borosilicate glass can be designed to be thin yet durable, or thicker for added strength. They are generally microwave- and dishwasher-safe, offering convenience and versatility in the kitchen.

Why is borosilicate glass often chosen for lenses in high-quality flashlights?

Borosilicate glass is used for lenses in many high-quality flashlights because it offers superior light transmittance compared to plastics and lower-quality glass. This results in a brighter, clearer beam of light.

Which types of high-intensity discharge (HID) lamps commonly use borosilicate glass?

Several types of HID lamps, including mercury-vapor lamps and metal-halide lamps, utilize borosilicate glass as the material for their outer envelope. This provides protection and containment for the internal components.

How has lampworking with borosilicate glass influenced artistic applications?

Advancements in lampworking techniques, which involve using a torch to shape glass, have opened up new artistic possibilities with borosilicate glass. Artists can create a wide range of decorative and functional items.

What kinds of artistic products are created by artists using borosilicate glass in lampworking?

Artists utilize borosilicate glass in lampworking to create diverse products such as jewelry, kitchenware, sculptures, and artistic glass smoking pipes. The material's workability and durability lend themselves to intricate designs.

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What is Borosilicate Glass?

Definition and Composition

Borosilicate glass is a specialized type of glass characterized by its primary constituents: silica (SiO₂) and boron trioxide (B₂O₃). This unique composition imparts exceptional properties that distinguish it from common glass types.

Superior Thermal Properties

Its defining feature is an exceptionally low coefficient of thermal expansion, approximately 3.3 × 10⁻⁶ K⁻¹ at 20°C. This property makes it highly resistant to thermal shock, allowing it to withstand significant temperature differentials (around 166°C) without fracturing, a critical advantage in many demanding applications.

Comparison and Applications

While soda-lime glass is more common for general use, borosilicate glass excels where thermal stability and chemical resistance are paramount. It is extensively used for laboratory glassware, lighting components, electronic applications, and high-quality cookware.

A Legacy of Innovation

The Genesis in Jena

The foundation of borosilicate glass was laid in the late 19th century by German glassmaker Otto Schott in Jena. This early formulation became known as "Jena glass," pioneering the use of boron trioxide in glass manufacturing.

Pyrex and Global Recognition

Corning Glass Works introduced Pyrex in 1915, popularizing borosilicate glass in the English-speaking world. While the Pyrex brand has since expanded to include soda-lime glass products, its origin is deeply tied to the superior thermal resistance of borosilicate formulations.

Material Composition

Key Constituents

Borosilicate glass is primarily composed of approximately 80% silica (SiO₂) and 13% boron trioxide (B₂O₃). It also typically includes around 4% sodium oxide (Na₂O) or potassium oxide (K₂O), and 2-3% aluminum oxide (Al₂O₃). This precise blend dictates its characteristic properties.

Thermal Characteristics

The glass typically melts around 1,650°C (3,000°F). Its low thermal expansion coefficient (3.3 x 10⁻⁶ K⁻¹) is significantly lower than that of ordinary soda-lime glass (around 9 x 10⁻⁶ K⁻¹), contributing to its remarkable resistance to thermal stress and fracture.

Defining Physical Characteristics

Thermal Shock Resistance

The low thermal expansion minimizes internal stresses when subjected to temperature changes. This allows borosilicate glass to withstand temperature differentials of approximately 170°C, far exceeding the capabilities of standard glass, making it ideal for applications involving rapid heating or cooling.

Chemical Durability

Borosilicate glass exhibits excellent resistance to chemical corrosion, even under harsh conditions. Tests for acid resistance reveal minimal impact, ensuring its integrity in laboratory environments where it frequently contacts various chemical reagents.

Optical Clarity

Optically, it functions as a crown glass, characterized by low dispersion (Abbe numbers around 65) and relatively low refractive indices (1.51–1.54). This clarity is essential for precise optical instruments and scientific observations.

Viscosity and Working Temperature

The softening point, where viscosity reaches approximately 10⁷·⁶ poise, is around 820°C for common types like Pyrex 7740. Industrially, its workable temperature requires specialized techniques, often involving oxygen-fuel torches, reflecting its higher melting point.

Manufacturing Techniques

Production Methods

The creation of borosilicate glass products utilizes various methods tailored to the desired geometry. These include the float process for flat glass, tube drawing for hollow forms, and molding for specific shapes. Each technique leverages the unique rheological properties of molten borosilicate glass.

Classifying Borosilicate Glass

Non-Alkaline-Earth Borosilicates

This common category, often designated as borosilicate 3.3, features high silica (>80%) and moderate boron trioxide (12-13%). It offers the lowest thermal expansion among commercial glasses and excellent chemical durability, making it highly versatile for technical applications.

Alkaline-Earth Borosilicates

Containing approximately 75% silica, 8-12% boron trioxide, and up to 5% alkaline earth oxides and alumina, these variants are slightly softer. They exhibit thermal expansions in the range of 4.0–5.0 × 10⁻⁶ K⁻¹, offering a balance of properties for specific uses.

High-Borate Formulations

With boron trioxide content ranging from 15-25%, these glasses possess lower softening points and reduced chemical resistance compared to other borosilicates. However, they can offer enhanced UV transmission and unique sealing capabilities with certain metals.

Diverse Applications

Health and Science

Virtually all modern laboratory glassware, including beakers and flasks, is crafted from borosilicate glass due to its thermal and chemical resilience. It is also crucial for parenteral drug packaging (vials, syringes) and implantable medical devices, ensuring purity and stability.

Electronics and Lighting

In electronics, it's used in microelectromechanical systems (MEMS) and historically in high-power vacuum tubes. For lighting, borosilicate glass serves as lenses in flashlights and outer envelopes for high-intensity discharge lamps, maximizing light transmittance.

Cookware and Tableware

Its thermal shock resistance makes it ideal for bakeware, measuring cups, and durable beverage glassware, particularly items intended for hot liquids. Many borosilicate items are microwave and dishwasher-safe, offering convenience and longevity.

Optics and Precision Instruments

Borosilicate glass is fundamental in optics, used for telescope mirrors (like the Hale Telescope's primary mirror) and precision lenses (e.g., Schott BK7). Its low thermal expansion ensures optical stability, critical for accurate measurements and imaging.

Advanced Manufacturing

In additive manufacturing, borosilicate glass is the material of choice for fused deposition modeling (FDM) build plates. Its thermal stability and flatness minimize warping during printing, ensuring reliable adhesion and part quality.

Aerospace and Energy

Borosilicate glass finds application in spacecraft heat shields (e.g., Space Shuttle, SpaceX Starship) and evacuated-tube solar thermal collectors, leveraging its strength and heat resistance in extreme environments.

Waste Management

It is employed in the immobilization and disposal of radioactive waste through vitrification, offering exceptional chemical durability that ensures containment for millennia.

Prominent Trade Names

Recognized Brands

Borosilicate glass is marketed under various trade names globally, reflecting its widespread adoption and specialized formulations. Some notable examples include:

Borofloat (Schott AG)
Duran (DURAN Group)
Pyrex (Corning Inc.)
Kimax (Kimble)
Simax (Kavalierglass)
BK7 (Schott AG - for optical applications)
Fiolax (Schott AG - for pharmaceutical containers)

Borosil (India - laboratory and kitchenware)
Rasotherm (VEB Jenaer Glaswerk Schott & Genossen)
Supertek (Scientific lab equipment)
United Scientific (Laboratory glassware)
Willow Glass (Corning - alkali-free, flexible)
Boroux (Drinking bottles)
Endural (Holophane)

Specialized Forms and Techniques

Nanoparticles and Lampworking

Researchers have successfully synthesized borosilicate nanoparticles, enabling novel applications. In artistic and scientific glassblowing (lampworking), borosilicate is favored for its higher melting point ("hard glass") compared to soft glass, allowing for intricate scientific apparatus, artistic sculptures, and durable smoking pipes.

Artistic Applications

The development of colored borosilicate glass rods by companies like Northstar Glassworks has fueled artistic expression. Artists utilize its properties for creating vibrant beads, pendants, and complex glass art, appreciating its strength and predictable behavior under a torch flame.

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References

M. I. Ojovan and W.E. Lee. An Introduction to Nuclear Waste Immobilisation, Elsevier, Amsterdam, 315 p. (2005)

Chemical & Engineering News Vol. 86 No. 37, 15 September 2008, "Making Borosilicate nanoparticles is now possible", p. 35

Robert Mickelsen, "Art Glass Lampworking History" Online Glass Museum, http://www.theglassmuseum.com/lampwork.html

A full list of references for this article are available at the Borosilicate glass Wikipedia page

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This page was generated by an Artificial Intelligence and is intended for informational and educational purposes only. The content is derived from publicly available data and may not be exhaustive or entirely up-to-date.

This is not professional advice. The information provided herein is not a substitute for expert consultation in material science, engineering, or manufacturing. Always refer to official documentation and consult qualified professionals for specific applications and requirements.

The creators of this page are not responsible for any errors or omissions, or for any actions taken based on the information provided.

Borosilicate Brilliance

💡 Dive in with Flashcard Learning! 💡

What is Borosilicate Glass? 🧪

💎 Definition and Composition

🌡️ Superior Thermal Properties

⚖️ Comparison and Applications

A Legacy of Innovation 📜

🇩🇪 The Genesis in Jena

🇺🇸 Pyrex and Global Recognition

Material Composition 🔬

🧪 Key Constituents

🔥 Thermal Characteristics

Defining Physical Characteristics 📏

❄️ Thermal Shock Resistance

அமில Chemical Durability

💡 Optical Clarity

⚙️ Viscosity and Working Temperature

Manufacturing Techniques 🏭

⚙️ Production Methods

Classifying Borosilicate Glass 🧬

🔬 Non-Alkaline-Earth Borosilicates

🧪 Alkaline-Earth Borosilicates

✨ High-Borate Formulations

Diverse Applications 🚀

🔬 Health and Science

💡 Electronics and Lighting

🍽️ Cookware and Tableware

🔭 Optics and Precision Instruments

🖨️ Advanced Manufacturing

🚀 Aerospace and Energy

☢️ Waste Management

Prominent Trade Names 🏷️

🏢 Recognized Brands

Specialized Forms and Techniques ✨

🔬 Nanoparticles and Lampworking

🎨 Artistic Applications

Teacher's Corner 🧑‍🏫

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References

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📜 Important Notice

Dive in with Flashcard Learning!

What is Borosilicate Glass?

Definition and Composition

Superior Thermal Properties

Comparison and Applications

A Legacy of Innovation

The Genesis in Jena

Pyrex and Global Recognition

Material Composition

Key Constituents

Thermal Characteristics

Defining Physical Characteristics

Thermal Shock Resistance

Chemical Durability

Optical Clarity

Viscosity and Working Temperature

Manufacturing Techniques

Production Methods

Classifying Borosilicate Glass

Non-Alkaline-Earth Borosilicates

Alkaline-Earth Borosilicates

High-Borate Formulations

Diverse Applications

Health and Science

Electronics and Lighting

Cookware and Tableware

Optics and Precision Instruments

Advanced Manufacturing

Aerospace and Energy

Waste Management

Prominent Trade Names

Recognized Brands

Specialized Forms and Techniques

Nanoparticles and Lampworking

Artistic Applications

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice