There really is nothing else quite like Boron Nitride !!! read on !!
Boron Nitride in Manufacturing Tool Applications
A new form of cubic boron nitride is used for coating machining tools in high-power and high-speed electronics.Scientists at North Carolina University have managed to create a new phase of the ceramic cubic boron nitride (c-BN) that will have future applications in developing high-power and high-speed electronics. The new ceramic can be used for coating cutting and other machining tools to stop them reacting with other materials at high temperatures, pressures and voltages.
The key achievement has been to develop a faster and less expensive method of creating c-BN and so make it a potentially viable substitute for diamond in machining tools.
Boron nitride has a high chemical and thermal resistance and, like carbon, exists in a number of crystalline forms. The most common of these are a hexagonal version similar to graphene and a cubic version similar to diamond.
However, C-BN is not only harder than diamond. Unlike diamond, it will not react with iron and other ferrous materials during a high-power and high-temperature machining process. A further advantage of c-BN over diamond is its high bandgap – the minimum level of energy needed for an electron in the crustal to be released so it can act as a conductor. This means it can be used at higher temperatures than diamond, especially in the oxygen-rich environments where many machining tools are operational.
The c-BN production process starts with a layer of hexagonal boron nitride (h-BN) that may be between 5000 and 1,000 nanometres (nm) thick. The scientists place this material on a substrate and apply pulses of high-power laser to heat h-BN to around 2,530 degree Celsius, after which the heat is rapidly quenched by the substrate. The entire process can take as little as one fifth of a nanosecond.
The conversion of h-BN to c-BN is controlled by manipulating the cooling time of the substrate. This process will also determine whether the c-BN will developed into microcrystals, a film or nanoneedles or nanodots. The scientists say that it takes just one second to create a c-BN film in a size range between 100 and 200 square inches.
This is a significant improvement upon earlier techniques of creating c-BN that required heating h-BN to 3,230 degrees Celsius in a pressure of 95,000 atmospheres.
A further advantage of the new process for creating c-BN is that the final product can be “doped” to give it negatively and positively charged layers. This resulting material can be used for transistors and other solid state electronics.
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