Fused quartz, the uncompromising lab ware

Sept. 1, 2010

When lab ware applications demand superior properties — chemical purity, thermal shock resistance, light transmission, and other advanced performance characteristics — the right material is fused quartz.

Quartz lab ware offers users exceptional mechanical, electrical, optical, and thermal properties that provide uncompromising performance for a wide range of robust applications throughout science and industry. A wide variety of fused-quartz lab products are available, including flasks, beakers, test tubes, joints, dishes, crucibles and cuvettes, for the wide variety of functions required in the medical laboratory (e.g., volumetric measuring, holding or storing chemicals or samples, mixing or preparing solutions and other mixtures, containing lab processes like chemical reactions, distillation, separations including chromatography and spectrophotometry, and more. Since virtually all quartz lab ware is individually hand blown, customer-specified pieces are also available.

Unmatched thermal properties
Fused quartz is superior to borosilicate when it comes to heat. Fused quartz is a solid material at room temperature. At high temperatures, it behaves like all glasses. It does not experience a distinct melting point as crystalline materials do, but softens over a fairly broad temperature range. This transition from a solid to a plastic-like behavior is distinguished by a continuous change in viscosity (resistance to changing shape) with temperature.

Fused quartz products, including lab ware, can be heated to 1,150^0C under minimal load conditions. It can then be plunged into cold water without cracking, due to its related property of high thermal shock resistance. The annealing point is 1,140^0C; strain point is 1,070^0C; fusion point is between 1,700^0C and 1,800^0C.

“In practical lab applications, the thermal stability of fused quartz can be related to safety,” says Doug Sisson, president of DC Scientific, Pasadena, MD, a manufacturer of glassware including fused-quartz lab ware.

While heating glass in a medical laboratory is not a usual occurrence, the durability of fused quartz is unquestioned. “We have customers in the petrochemical industry that use quartz flasks for heating materials such as gasoline. If those were borosilicate flasks and they were set on top of a heater, the borosilicate flasks could break and create a fire. Flasks made of fused quartz, because of the extremely high temperature properties and the low coefficient of expansion, will not break due to the heat or temperature shock. It saves time. They are more expensive, but the quartz vessels are much safer and will also last longer,” Sisson explains.

Exceptional purity
Fused-quartz purity levels are unsurpassed in the glassware industry, and are much superior to borosilicate products.

“The performance of most fused-quartz products is closely related to the purity of the material,” explains James Horvath, president of Technical Glass Products (TGP), Painesville, OH, a distributor and fabricator of fused-quartz material. “The purity of raw material and fusion processes must be closely monitored and controlled, which can yield products with typically less than 50 ppm total elemental impurities by weight. This is extremely pure when compared with borosilicate, although it also has a wide range of laboratory applications. TGP also manufactures borosilicate glassware, so Horvath is keenly aware of the properties and benefits of both products.

“The chemical purity and inertness of quartz are essential to many lab applications,” Horvath continues. “If a lab vessel reacts with the reagent it holds, that may be highly problematic. Also, if a glass component leaches into the reagent, that will affect the outcome of test. So, the chemical purity is a major reason why some users choose vessels made of fused quartz.”

Horvath adds that the optical purity of quartz that may be equally important to many users. The transmisivity, or ability of a relatively broad range of light wavelengths to pass unimpeded through clear quartz lab ware, can be vital to many experiments.

“For UV or infrared applications, you want to have very good optical transmission at specific wavelengths,” says Horvath.

Mechanical toughness
“The material is also very inert and, therefore, highly chemical resistant,” Horvath says. “If you were using a glass beaker, for example, that could react with a solution it contained, that would corrupt the solution. Fused-quartz lab ware is rarely attacked by any acid, except a fluorine-based gas or solution. It can withstand exposure to many acids, even at very high temperatures, for up to months and even years.”

Quartz also makes an excellent electric insulator. Both electrical insulation and microwave transmission properties are retained at very high temperatures and over a wide range of frequencies.
Quartz lab ware offers users exceptional mechanical, electrical, optical, and thermal properties that provide uncompromising performance for a wide range of robust applications throughout science and industry.

“Many of the properties of fused quartz make it ideal for many industrial applications as well,” says DC Scientific’s Sisson. “We have customers who use it for burning in IC chips, for example, because of their high temperature, high purity, and UV transmission requirements. We also have customers in the petroleum industry that use quartz lab ware for many of the same reasons.”

The applications of TGP customers range from semiconductor to fiber optic and photovoltaic (solar) cell manufacturing, specialty lighting, aerospace, and pharmaceutical and university laboratories. For many of them, TGP offers custom design and technical services, as well as the necessary production capabilities.

“In addition to quality, we care about the availability of technical support and other value-added services,” Sisson adds. “Flexibility on order quantities and timely deliveries are important, too.”

Louise Townsend is a Florida-based writer who formerly specialized in legislative issues for a major Washington, DC, pharmaceutical association.

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