ارتباط با ما
با ما تماس بگیرید
0086-21-58386256
0086-21-58386256
Boron carbide is an advanced non-oxide ceramic. It possesses a set of outstanding properties such as a high melting point, high thermal stability, low density, high mechanical strength, extreme hardness and a high neutron absorption cross section [1,2,3].These excellent properties make boron carbide a promising material for various …
Some of these particulates are composed of boron carbide—an ultra-tough substance used for coating drill bits. You can imagine its effect inside a jet engine full of spinning, high-precision parts.
Properties and applications. Until the invention of boron carbide in 1929, silicon carbide was the hardest synthetic material known. It has a Mohs hardness rating of 9, approaching that of diamond. In addition to hardness, silicon carbide crystals have fracture characteristics that make them extremely useful in grinding wheels and in abrasive paper …
The present invention relates to boron carbide powder rich in 10B and a preparation method thereof. The preparation method comprises the following steps of: performing ball-mill mixing on 75 to 85 parts of the boron carbide powder with the 10B abundance of 40 to 96 percent and 15 to 25 parts of carbon powder, and performing calcination on the …
This invention describes the deposition of boron and silicon carbide films using a novel fabrication method. Prior to this invention, deposition of boron containing materials via charged particle induced dissociation of boron precursor molecules had not been demonstrated. ... This is the first demonstrated technology which can rapidly prototype ...
The invention is directed to the preparation of boron carbide articles of various configurations. ... In accordance with the method of the invention a mixture of 5 to 10 vol. % silicon carbide whiskers 0.5 to 5 wt. % of a sintering aid such as yttria and the balance alumina powders is ball-milled and pressureless sintered in the desired ...
Modern Uses of Boron . The invention of thermally stable borosilicate glass in the late 1800s provided a new source of demand for borate minerals. Making use of this technology, Corning Glass Works …
In a preferred embodiment of the invention related specifically to armor, good ballistic performance can be advanced by loading the porous mass or preform to be infiltrated to a high degree with one or more hard fillers such as boron carbide, and by limiting the size of the morphological features, particularly the ceramic phases, making up the ...
The boron carbide coated boron particles formed can be used in solid propellant or ramjet fuels. The ceramic boron carbide coating on the particles protects the boron metal and alleviates the agglomeration of boron particles. Therefore, it is believed that the critical thrust performance/weight ratio is improved using the present invention.
The present invention is directed to the fabrication of boron carbide articles having length-to-diameter or width ratios greater than 2 to 1. The process of the present invention is practiced by the steps comprising hot pressing boron carbide powder into article segments or portions in which the segments have a length-to-diameter or width ratio ...
The present invention is directed to the fabrication of boron carbide articles having length-to-diameter or width ratios greater than 2 to 1. The process of the present invention is practiced by the steps comprising hot pressing boron carbide powder into article segments or portions in which the segments have a length-to-diameter or width …
Boron carbide is one of the hardest materials in the world which can be synthesized by various methods. The most common one is a carbothermic or magnesiothermic reduction of B2O3 performed at high temperatures, where the obtained powder still requires grinding and purification. The goal of this research is to present the …
At a temperature of 1800°C, a boron carbide content in the charge of 25.3% (by weight) and a holding time of 30 min, titanium diboride with an average particle size of about 1 μm was obtained. It should be noted that the calculated content of boron carbide in the charge as applied to the reaction (12) is 22.2% (by weight).
The invention relates to pure boron carbide (B4C) production method comprising subjecting saccharose (table sugar) to dehydration reaction with the sulphuric acid in the presence of boric acid, obtaining the precursor (12C+48B) comprising carbon and boron as a result of the said dehydration reaction, subjecting the obtained precursor to the heat …
Boron carbide is produced by reducing boron oxide with carbon at high temperatures in an electric furnace. After grinding, the black powder is solidified by pressing at temperatures exceeding 2,000° C (3,630° F).
In the synthesis of boron carbide allotropes, the role played by carbon is relatively overwhelming. Therefore, being a fundamental precursor for both solid and …
Single crystals of boron-carbide were grown at high pressures of 8.5–9 GPa and high temperatures of 1873–2073 K using a 1200-ton (Sumitomo) multi-anvil hydraulic …
The present invention is directed to the fabrication of boron carbide articles having length-to-diameter or width ratios greater than 2 to 1. The process of the present invention is practiced by the steps comprising hot pressing boron carbide powder into article segments or portions in which the segments have a length-to-diameter or width ratio ...
Boron carbide (B 4 C) Is a useful ceramic compound. B 4 C is third hardest material known, following diamond and cubic boron nitride (cBN). B 4 C is hard, lightweight, and wear resistant, making it attractive for such applications as sandblasting nozzles, bearings, dies, lapping and polishing abrasive powders, sporting equipment (as part of a metal matrix …
boron carbide, (B 4 C), crystalline compound of boron and carbon.It is an extremely hard, synthetically produced material that is used in abrasive and wear-resistant products, in lightweight composite materials, and in …
Boron carbide is the lightest and hardest ceramic known to man. ... By way of example, in one alternative embodiment of the invention the plug is made of the same boron carbide material but the outer periphery of the plug is coated with a parting material made of the same combination previously described, namely, graphite flake, carbon black ...
This invention relates to the preparation of a highly densified boron carbide ceramic body by the pyrolysis of a mixture comprising boron carbide powder and a preceramic organosilicon polymer selected from the group consisting of polysiloxanes, polysilazanes, polysilanes, metallopolysiloxanes and metallopolysilanes. Such highly densified ceramic …
For reference, Fig. 7.15 shows the boron-rich corner of the B–C phase diagram. Boron carbide is a covalently bonded solid with a high melting point (2427°C), outstanding hardness (Vickers: 3770 kg/mm 2), good mechanical properties and low specific gravity (2.52 g/cm 2), making it ideal for use in lightweight armours.The nominal boron carbide …
Boron carbide is useful for applications where ultra-hard components are needed, such as wear-resistant bearings, sand-blasting nozzles, abrasives and ballistic armor. There are significant challenges, such as the high temperatures required and particle coarsening, associated with the pressureless sintering of boron carbide (B 4 C).
Landmark Designation. The American Chemical Society designated the development of high performance carbon fibers at Union Carbide (now GrafTech International, Ltd.) in Parma, Ohio, as a National Historic Chemical Landmark on September 17, 2003. The plaque commemorating the development reads:
In the hot-pressing operation, the B 4 C powder is first cold pressed into pellet form and then hot pressed in graphite dies at temperatures from 2050 to 2300 °C under pressure …
This invention relates to metal-ceramic composite bodies produced by a reactive infiltration process, e.g., reaction-bonded bodies. More particularly, the invention relates to reaction-bonded silicon carbide having a boron carbide filler or reinforcement, and to ballistic armor structures produced from reaction-bonded silicon carbide bodies.
The PECVD boat as claimed in claim 1, wherein the hard-material coating comprises a combination of titanium nitride, titanium carbide and boron carbide. 5. The PECVD boat as claimed in claim 1, wherein the hard-material coating has a multilayer construction comprising boron carbide and at least one of titanium carbide and titanium nitride. 6.
Background. Boron Carbide (B 4 C) is one of the hardest materials known, ranking third behind diamond and cubic boron nitride. It is the hardest material produced in tonnage quantities. Originally discovered in mid 19 th century as a by-product in the production of metal borides, boron carbide was only studied in detail since 1930.. Boron …
According to my invention a solid solution of 1 coke which always contain iron thus, enabling I one to produce a high quality product on a large scale and in an economical way, which, hitherto, could be produced -in the laboratory only. ... The process of making a boron carbide material, free of free elementary carbon and consisting ...
The method of preparing a sintered boron carbide material of the invention employs washing boron carbide powder with essentially pure water at an elevated temperature to generate low oxygen (less than about 3 wt % O 2) boron carbide powder. The boron carbide powder suitable for use in the invention can be amorphous or crystalline.
41 Citations 3 Altmetric Metrics Abstract The ternary compound boron carbonitride (BCN) was synthesized in the form of few-layer nanosheets through a mechanically induced self-sustaining reaction...
The developed technology for the electric melting of boron carbide in an electric furnace, of the described design, allows to obtain a block of boron carbide of the …
Boron carbide is one of the hardest substances, surpassed only by diamond and boron nitride 1. The high mechanical and thermal stability, low density and low costs of fabrication have made boron ...
This invention describes the deposition of boron and silicon carbide films using a novel fabrication method. Prior to this invention, deposition of boron containing materials via …
A method of depositing boron carbide on an aluminum substrate, particularly useful for a plasma etch reactor having interior surfaces facing the plasma composed of boron carbide, preferably principally composed of B 4 C. Although in this application, the boron carbide may be a bulk sintered body, in the method of the invention it may be a layer of boron …
The PECVD boat as claimed in claim 1, wherein the hard-material coating has a multilayer construction comprising boron carbide and at least one of titanium carbide and titanium nitride. Description: The invention relates to a protective layer for PECVD boats made of graphite for receiving wafers and for transporting same in or through PECVD ...
Substantially all of the boron carbide produced by the method of the present invention contains a boron to carbon (B:C) ratio near the theoretical formula B 4 C and the boron carbide is substantially free of excess carbon. The boron carbide powder produced by the method of the present invention may be used for example, in making armor plates ...
The present invention is directed to the preparation of boroncarbide articles of various configurations. A stoichiometric mixture of particulate boron and carbon is confined in a suitable mold, heated to a temperature in the range of about 1,250* to 1,500*C. for effecting a solid state diffusion reaction between the boron and carbon for forming the boron …
