IMPORTANT: To ensure maximum crucible life and safety of the operator, read instructions carefully before performing fusion.
Oxidation is not a serious problem with zirconium in sodium peroxide fusions. With sodium or potassium carbonate fusions, the reducing flame of a Bunsen burner (except for finishing the fusion) is far preferable to a muffle furnace.
NEVER use a muffle furnace with zirconium unless a blanket of inert gas such as argon or helium is also used.
Zirconium metal reacts, when heated in air, to form a dark mixed surface layer of oxide plus nitride. It is not necessary to remove this layer between successive fusions. If occasional scouring becomes necessary, fine zircon sand has proven most effective. Crucible cleaning kits are available: Part Number: 90-100.
For best results in peroxide or peroxide-plus-carbonate fusions, use a finely ground sample and about ten times the sample weight of flux material. Mix well. Fusion should be completed 2 to 3 minutes after melting begins at 600-700°C. Gentle swirling of the molten mixture at room temperature and while cooling accelerates decomposition of sample and increases life of crucible.
DO NOT EXCEED 900°C or zirconium crucibles will enlarge and oxidize (turn pinkish white).
Zirconium Crucibles – Extremely Corrosion Resistant Metal
The remarkable corrosion resistant qualities of Zirconium are used extensively in the Chemical Processing Industry. Zirconium can withstand a wider range of caustics and acids than any other commonly used fabricating material. We manufacture zirconium crucibles at our plant in Aldridge just a few minutes away from Birmingham. From this location, Winward Engineering Ltd is ideally placed to supply the entire UK.
Zirconium Crucibles Information – Facts And Advantages
It is no secret that zirconium crucibles cost more than porcelain, steel or nickel. Quite a bit more. But, based on an average number of fusions which can be made in a zirconium crucible, as opposed to those of nickel, the ratio of longevity stands at 20 to 1. Therefore, the higher cost of zirconium crucibles is recovered three times over. In addition to cost effectiveness, zirconium crucibles hold several advantages over other materials.
If compared to platinum crucibles, several distinct advantages are readily apparent.
Improper procedure in heating over a Bunsen burner can cause the reducible contents to be converted into harmful, low-fusing metals which may react with the platinum crucibles.
No platinum tipped tongs or special triangles are required for handling hot zirconium crucibles.
Sudden contact with cold, metallic surfaces will have no deleterious effects on a zirconium crucible.
Hydrofluoric acid is the only cleaning agent which should not be used to clean zirconium crucibles.
Smoothing and shaping after use is not a special consideration. Zirconium crucibles require a minimum of specialized care.
The inherent strength of zirconium precludes the necessity of reinforced rims and thicker bottoms as is the case of platinum crucibles in certain instances.
Zirconium crucibles are especially adaptable to the needs of the analytical chemistry laboratory, such as in strong alkaline fusions employed to reduce refractory samples to a soluble form, and for high temperature ignition ashing purposes.
Zirconium metal is a most effective all-round crucible for fusions using sodium carbonate or sodium peroxide and is an excellent low-cost replacement for platinum crucibles. Based on an average of 100 fusions per crucible, zirconium is more cost-effective than less expensive crucibles of porcelain or steel.
Heating/Cooling Information
Excellent low cost replacement to platinum.
Does not require handling with platinum tipped tongs.
Virtually eliminates sample contamination.
Effective all round crucible for fusions employing sodium carbonate and sodium peroxide.
Under vacuum can be heated to 1450°C.
Tariff Code : 8109 90 00
Many regard Zirconium as a rare metal yet it is not uncommon but an exotic material. Zirconium, however, has many rare, even unique, qualities such as its remarkable corrosion resistance, being used extensively in the chemical processing industry. Zirconium will withstand a range of caustics and acids to a greater degree than any other commonly used metal and stands in a class by itself.
Cleaning Zirconium Crucibles
Hydrofluoric acid is the only cleaning agent that should not be used to clean zirconium crucibles.
Applications For Zirconium Crucibles
Zirconium crucibles are suitable for several applications in the analytical chemistry.
Sodium Peroxide Fusions – used with refractory or high-silica materials such as chromate, magnetite, illmenite, retile, silicon, silicon carbide, and certain alloys and steels. An excellent general flux for almost any material.
Sodium Carbonate Fusions – decomposes most silicates of aluminum, calcium, chromium, nickel; also halides of silver; and sulphates of barium and lead.
Lithium Salt Fusions – flux for oxide and silicate materials when sodium and potassium need to be determined or when large amounts of sodium would interfere with x-ray fluorescence or atomic absorption procedures.
Fusions In Zirconium Crucibles
Fusions are best made in the reducing flame of the burner where there is little or no attack or oxidation of the crucible – regardless of the sample material or flux mixture.
In making fusions, the sample is mixed with 4 to 10 times its weight of flux and placed over a bed of flux in the crucible. The burner set-up should be under a fume-hood and positioned under a Tripod Initially, the crucible and contents should be gently introduced over the flame, moving it in and out as melting commences. When molten, the heat can be raised and the contents ‘swirled’ to keep the sample off the bottom – use any Stainless Steel tongs to handle the crucible and accomplish the swirling action, which should be continued throughout the fusion process.
When molten it either becomes clear/homogeneous, or a very bright red, the fusion is now complete. The fused mass can be allowed to solidify in the crucible. The crucible and contents can then be placed in a beaker covered with water and the suitable solvent added to remove the fused mass from the crucible. Any material adhered to crucible can be dissolved out with more solvent. Under these conditions only a few milligrams of zirconium will be introduced into the sample. If this trace needs removing it can be accomplished by using strong acid solution.