Injection boron carbides

MacKinnon and Wickens (37) have prepared boron carbide in the form of submicron particles by injecting BCI3, Hg, and CH into the tail of a 20-kW argon RF plasma. A 3 factorial experiment to study the effect of operating variables was carried out a preliminary analysis of which gave the following indications ... 

Figure 7—92. Thermal ICP reactor for boron carbide produetion by BCI3 eonversion in hydrocarbon plasma (1) RF generator, (2) discharge chamber, (3) argon injection system, (4) RF inductor, (5) water-cooling system, (6) distributor of reagents.

Injection molding of boron carbide with 2-5 mass.-% carbon black was developed by Schwetz et al. [210]. Like in conventional processes known for oxide and nitride ceramics, the spray-dried powder blend was mixed with 18 mass-% organic binder and molded at 120°C and 45 MPa. Dewaxing was accomplished by heating in an atmosphere-controlled furnace at 100 mbar. The binder components decomposed thermally by cracking and evaporated within four days and temperatures up to... 

Bimetallic cylinder n. In most modern extruders and injection machines, the barrel is lined, by centrifugal casting from the melt, with any of several white irons containing chromium and boron carbides and having hardnesses near Rockwell C65. Aster finish-grinding and polishing, the liner, about 1 mm thick, provides excellent resistance to wear or corrosion or both, depending on the formation. The best known trade name is XALOY . 

It is necessary to load 31 fuel assemblies with guide tubes for control rods (GT assemblies) to gain a satisfactory shutdown margin under cold zero power shutdown conditions. The Reactor Protection System comprises two independent fast acting shutdown systems. Shutdown System-1 (SDS-1) is based on mechanical shutdown rods with boron carbide based absorbers in 31 fuel assemblies it provides sufficient negative reactivity with all rods inserted, with one maximum worth rod not available, in the cold shut down condition. Shutdown system-2 (SDS-2) is based on liquid poison injection into the moderator. 

Bimetallic Cylinder n In most modern extruders and injection machines, the barrel is lined, by centrifugal casting from the melt, with any of several white irons containing chromium and boron carbides and having... 

The process is effectively stimnlated by argon heated up inside of the RF-ICP discharge and takes place downstream from the thermal discharge, where reactive gases are injected into argon (Tumanov, 1981 see Fig. 7-92). The yield achieved by the process is 93-95%, the composition of the boron chloride is close to a stoichiometric value Bs gC, the size of the produced particles is 200-300 nm, and the particles color varies from gray to black depending on the fraction of carbon in the carbide. 

The increasing use of plastics with abrasive fillers and reinforcements created a demand for an even more abrasion resistant barrel than the standard iron/boron type. The use of glass fiber reinforced compounds for injection molding has been the single most important factor since a fabricator would be lucky if they could reach 6 months of continuous operation. This need has been successfully answered by the development of liner materials containing metallic carbides such as tungsten carbide and titanium carbide extending their life. 

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