Borate glass powder

Lead borate moaohydrate [14720-53-7] (lead metaborate), Pb(B02)2 H20, mol wt 310.82, d = 5.6g/cm (anhydrous) is a white crystalline powder. The metaborate loses water of crystallization at 160°C and melts at 500°C. It is iasoluble ia water and alkaHes, but readily soluble ia nitric and hot acetic acid. Lead metaborate may be produced by a fusion of boric acid with lead carbonate or litharge. It also may be formed as a precipitate when a concentrated solution of lead nitrate is mixed with an excess of borax. The oxides of lead and boron are miscible and form clear lead-borate glasses in the range of 21 to 73 mol % PbO. 

B) Thermal treatment of glass obtained in stage A. The glass (in pieces or as crushed and sieved powder) is reheated for several hours to several days [16,17] to achieve phase separation and to increase the microheterogeneities which are the alkali-borate phase. The thermal history determines the later size of the CPG pores. The separation process for alkali-borate glasses occurs in the temperature range from about 500 to 700°C. 

Norrish, K. Hutton, J.T. (1964) Preparation of samples for analysis by X-ray fluorescence spectrography. 1. Lusion in borate glass. 2. Powder samples. CSIRO Div. of Soils Div. Rep. No.3. 

Solder Glass. The glass powder used in making glass-to-metal seals (q.v.) is essentially lead borate. 

Dehye-Scherrer Camera. Figure 11 illustrates the principle of the Debye - Scherrer camera, while Figure 12 shows schematically how the diffraction pattern is generated. A specimen of crystalline powder (ca. 0.1 mg) is placed in a borate glass capillary of diameter 0.3 - 1 mm and length ca. I cm, and the capillary is rotated about a specified axis. The film fits snugly inside the camera. 

The uses in the glass and ceramics industries reflect the diagonal relation between boron and silicon and the similarity of vitreous borate and silicate networks (pp. 203, 206 and 347). In the UK and continental Europe (but not in the USA or Japan) sodium perborate (p. 206) is a major constituent of washing powders since it hydrolyses to H2O2 and acts as a bleaching agent in very hot water ( 90°C) in the USA domestic washing machines rarely operate above 70°, at which temperature perborates are ineffective as bleaches. 

Acetone powder (1.5 g) was extracted 4 times with 0.1 M sodium borate buffer (pH 7.6) at 4°C, homogenizing each time with a glass grinder equipped with a Teflon pestle. The first extraction was carried out with 80 ml of the buffer, followed by 3 times with 70 ml each of the buffer. Each homogenate was centrifuged at 16,000 g for 5 min. All supernatants were combined. 

Borates, through their ability to act as glass network formers, can act as excellent char formers and drip suppressants in fire retardant applications. In many cases this involves processing into polymeric materials, leading to specific requirements for thermal stability and particle size. Most common borate materials, however, exhibit relatively low dehydration temperatures and may be unsuitable for use in many polymer systems. Zinc borates are often used because they have unusually high dehydration onset temperatures and can be produced as small particle size powders. 

Typical fillers calcium carbonate, talc, glass fiber, glass beads, glass flakes, silica flour, wollastonite, mica, sepiolite, magnesium hydroxide, carbon black, clay, metal powders (aluminum, iron, nickel), steel fiber, si-licium carbide, phenolic microspheres, wood fiber and flour, antimony trioxide, hydrotalcite, zinc borate, bismuth carbonate, red phosphorus, potassium-magnesium aluminosilicate, fly ash, hydromagnesite-huntite... 

Boron occurs in nature as part of oxygenated compounds, or borates, that have been known since ancient times for their use in glass and metal production. In 1808 Joseph-Lotiis Gay-Lussac and Louis Jacques Thenard of France and Humphry Davy of England discovered the element boron almost concurrently. Another century passed before boron was successfully isolated in pure form. Elemental boron in its amorphous form is a dark brown powder it is a yellowish-brown, hard, brittle solid in its monoclinic crystalline form. It melts at 2,300°C (4,172°E). Boron is unreactive to oxygen, water, acids, and alkalis. Boron compotmds burn yellow-green during the flame test. 

Anhydrous, fused sodium borate, borax glass, fused borax. Powder or glass-like plates becoming Opaque on exposure to air. Slowly so] in water. 

Walnut (Juglans regia) shell powder abrasive, gentle detergents Sodium borate decahydrate abrasive, gentle soaps Sodium borate decahydrate abrasive, glass polishing Cerium oxide... 

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