Other Uses for Boron
In addition to the most widely known uses for boron, there is a wide range of specialized applications.
Abrasives - Boron Nitride, Boron Carbide and metal borides, because of their extreme hardness and abrasiveness, are used in the manufacture of specialty saw blades and abrasive wheels. Both have very high melting points: 3350°C and 3000°C, respectively. Due to its high hardness, boron carbide powder is used as an abrasive in polishing and lapping applications, and also as a loose abrasive in cutting applications such as water jet cutting. It can also be used for dressing diamond tools. Boron carbide is produced by the reduction of boric acid with finely divided carbon in electric furnaces at a temperature between 1400-2300°C. Alternatively boric oxide may be reduced with carbon and magnesium. Boron Carbide Powder has a wide range of industrial applications including: Wear parts; Abrasives; Nuclear shielding; Ceramic Armor; and as a sintering aid. Parts made with boron carbide are harder and nearly 20-30% lighter compared to SiC or Al2O3 parts.
Biocides* – Whether used indoors or outdoors, borates are highly effective in helping to prevent the decay of wood and wood-based products, as well as their destruction from a variety of insects, yet are safe for people, pets and the environment that share their surroundings. Borates also work as a fungicide and as a preservative in non-wood materials such as synthetic polymers, rubber compounds, and paints and coatings, including during their storage and after they’ve been applied.
Cellulose Insulation -- Additives containing boron products are used in loose fill insulation materials based on cellulose fibers. The boron products provide beneficial flame retardant properties, as well as lower the toxicity of off-gases including carbon monoxide. Borates also provide pest-control* and inhibit mold growth in cellulose insulation, depending on the amount and form of borate used.
Charcoal Briquettes - Briquettes used in barbeque grills are typically composed of wood and mineral char, saw dust, borax, sodium nitrate, limestone and starch. Borax is mostly used as a mold release agent and perhaps may offer a longer life of the briquette due to the fire retardant properties of borates.
Corrosion Inhibitors – The alkalinity and strong buffering action of boron compounds makes it useful as part of solutions for preventing corrosion of ferrous metals. The principal use of borates in this field is probably in anti-freeze formulations. The value of borax in this application is enhanced by its high solubility in ethylene glycol, the major constituent for commercial antifreeze. Brake fluids and hydraulic systems in the motor industry also used boron compounds as a corrosion inhibitor, and it is also used as a corrosion inhibitor and a lubricant carrier in wire drawing.
Dyestuffs – Borates are used as buffers in the manufacture of dyestuffs and when dying of nylon carpets. In the dyeing process color level and dye penetration is important to control. A mild alkaline condition helps to optimize color levels and to keep the fiber clean. Borax Decahydrate and 5 mol borax solutions are known to give stable pH values at various concentrations and temperature levels. Borax Decahydrate is recommended for pH control in the dyeing of nylon carpet as it gives constant pH, periodic bath adjustments are reduced, prevents staining by the jute backing and allows better shade matching by precluding a high initial pH which affects some shades.
Electrolytic Capacitors -- An electrical capacitor is a device that stores electrical energy. There are two main types of capacitor, a ‘dry’ and a ‘wet’ type. It is constructed of two conducting surfaces separated by an insulating or dielectric medium. The ‘wet’ electrolytic capacitor differs in that one of the conducting surfaces is a metal plate while the other is a chemical compound. The dielectric is a thin film of oxide of the metal making up the metal plate.
Electrolytic Condensers – Borax Decahydrate and Boric acid are used to manufacture both wet and dry types of electrolytic condensers. The purity of the materials used is of prime importance.
Fuel Cells – Made from boric acid, sodium borohydride can be used as the hydrogen source in a new generation of fuel-cells. In this application, borates fight global warming through clean fuel cell technologies that feature borates as a hydrogen carrier.
Metal Plating – Boric acid is used to control pH during electrolysis, preventing nichol from cracking and pitting in the electroplating process of its plating. The process involves passing an electrical current through an electrolyte of nickel sulfate, nickel chloride and boric acid. Boric acid is also an intermediary in the manufacture of fluoborate salts used in plating solutions as fluoboric acid.
Nuclear Reactions - The boron isotope is used for neutron screening and also for the control of nuclear reactions. All the known type of nuclear power stations use boron compounds. Boron-containing ceramics are also used to contain oil spills and encapsulate nuclear wastes. Boron is used in radiation shielding to absorb fast neutrons in nuclear reactors. Boron-10, one of the naturally occurring isotopes of boron, is a good absorber of neutrons and is used in the control rods (steel and aluminum alloys consisting of 2% boron) of nuclear reactors, as a radiation shield and as a neutron detector. In some Nuclear Power Stations, boric acid is added into the cooling water in order to prevent exceeding reactivity. To minimize radiation effects Borated concrete, with a high concentration of boron can also be used.
Photography - Borates such as Sodium Metaborate (NaBO2) are used in photography as a buffering agent to control pH within tight limits for both black and white picture developing and in ensuring the correct color balance in developing color pictures.
Refractories – Boron compounds are used as stabilizers and bonding agents in refractory and refractory cements to increase insulation/refractory properties of the concretes, bricks and other construction materials. Refractory materials must perform in very high temperatures by reflecting heat, for example in steel production, glass melting operations and kilns for firing ceramics. In refractory bricks, boric acid is used in firebricks and castables that require high temperature resistance, corrosion and abrasion resistance. Boric acid and Borax Decahydrate act as secondary binders to give the refractory mixture sufficient strength to retain its shape and configuration until the ceramic bond forms.
Tanning – Boron is used in tanning including soaking of hides and skins, for stripping vegetable tans and for neutralizing chrome tans. Boron is also used with salt in the control of red heat in sheep skins. The mild alkalinity and the weak acidity of Borax Decahydrate and Boric acid makes them suitable for the tanning process. Borax helps in soaking the hides and skins while Boric acid neutralizes limed pelts. They have been used in the leather industry since the 1850’s.
Miscellaneous – Boron products are also used in:
- Dust mite control, to help mitigate the predominant cause of asthma attacks in children
- Insect control in wood preservatives* and insulation materials to help protect homes from insects and the elements
- Cancer-fighting treatments that use boron neutron capture therapy.
- Personal care products such as foot powders, eye lotions, bath salts, hair creams, shampoos, and emulsification and buffering ointments
- Nylon sizing
- Polishes, as an emulsifying agent
- Rubber latex, as a preservative
- Buffers to control pH in a range of processing solutions
- Anodizing baths and in the electrolyte itself
* Government registration or certification may be required for particular applications in certain countries