Ceramic and Metal Labware
Ceramic and metal labware is used in applications where standard glass or plastic devices are inadequate. This includes fusion, reaction, or incineration of samples for chemical analysis or material synthesis. Ceramic labware includes boats, crucibles, trays dishes, and discs. Crucibles are cup-shaped pieces of laboratory equipment used to contain chemical compounds when heating them to very high temperatures. The receptacle is usually made of porcelain or an inert metal. One of the earliest uses of platinum was to make crucibles. More recently, metals such as nickel and zirconium have been used. Crucibles are commonly used with a high temperature-resistant crucible cover (or lid) made of a similar material. Ceramic and metal labware is very important part of a chemical laboratory.
Crucibles, which are the most important ceramic and metal labware, are generally made of metals. A high purity alumina crucible is ideal for high temperature applications. Re-crystallized alumina is used in crucibles because it offers the best thermal shock resistance due to the larger grain size (up to 200mm is advantageous). A platinum crucible allows strong heat to be applied without danger of reaction of the charge with the crucibles. The alternatives are nickel and porcelain crucibles, which are much cheaper but cannot be used at higher temperatures, and react more readily with a charge. Graphite crucibles can be taken to high temperatures without melting, but are reactive and are even consumed through heating in air. A metal crucible is placed into a furnace and, after the liquid is melted, the metal is taken out of the furnace and poured into a mold. Refractory materials retain their strength at high temperatures. They are used to make crucibles and to make refractory linings, which line furnaces, kilns, and incinerators. Refractories must be chosen according to the conditions they will encounter. For example, acidic refractories cannot be used in a basic environment and basic refractories cannot be used in an acidic environment because they get eroded when used improperly. Another important labware is a funnel. A funnel is a conically shaped pipe, employed as a device to channel liquid or fine-grained substances into containers with a small opening. Industrial funnels are usually made of either stainless sheet metal or ceramics. Ceramic and metal labware is manufactured to meet most industry specifications.
Ceramic and metal labware are used in many applications. Examples include their use in chemical analysis and ash content determination. Ceramic and metal labware must be strong at high temperatures, resistant to thermal shock, chemically inert, and have low thermal conductivities and coefficients of expansion.
