Sintered tungsten carbide

The LDPE production with tubular reactors (see Section 5.1) requires some sophisticated control valves [45]. The let-down valve (Fig. 4.2-6 B) controls the polymerization reaction via the pressure and temperature by a high-speed hydraulic actuator (9) together with an electronic hydraulic transducer. The position of the valve relative to the stem is determined by a high-resolution electronic positioner (7). The cone-shaped end of the valve stem (2), as well as the shrunk valve seat (3) are made from wear-resistant materials (e.g., sintered tungsten carbide) in order to tolerate the high differential pressure of around 3000 bar during the expansion of the polymer at that location. 

Parameters of sintered tungsten carbide with variable cobalt content and strength characteristics calculated from Palmquist cracks (specification based on tests of Peters, 1979)... 

A synthetic or man-made diamond material is now available which is extremely tough with a hardness approaching that of natural diamond. A layer of this synthetic diamond material is bonded to a tough shock-resisting base of cemented carbide for use in the form of tips. The range of application is on non-ferrous metals such as aluminium alloys, magnesium alloys, copper, brass, bronze and zinc alloys and non-metallic materials such as ceramics, porcelain and plastics. This material will also machine fully sintered tungsten carbide. 

Composites of interstitial alloys and metals are encountered in this class of ceramic, in particular the system sintered tungsten carbide-cobalt, which is used in metal cutting tools. 

Sintered tungsten carbide with a high abrasion resistance and good thermal conductivity, for nozzle tips and pin guides ... 

The cake discharges at the rear of the beach, between the beach proper and the rear hub. In its simplest form, the cake discharge will he a series of radial holes around the beach end. These holes will usually be lined with some form of erosion protection, quite often in the form of a sintered tungsten carbide... 

On the pillars of the 360° discharge, half cylinders of sintered tungsten carbide are used. The latest development of this component, by Alfa Laval, is to use a saddle shape, which improves the wear life of the component. 

Brinnel hardness. An indentation is made by a 10-mm-diameter hardened steel or sintered tungsten carbide ball. A load of 500 kgf is used for soft metals, and 3000 kgf for hard metals. Brinnell hardness is equal to the load in kilograms divided by the surface area in square millimeters of the impression made in the test material. 

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