Tham khảo tài liệu 'materials handbook 15th ed - g. brady_ h. clauser_ j. vaccari (mcgraw-hill_ 2002) episode 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 320 DOUGLAS FIR but may be colored by impurities to cream gray pink green or black. For furnace linings it is calcined but for fluxing it is simply crushed. The raw dolomite marketed by Basic Refractories Inc. for open-hearth steel making is washed crushed stone in size. When calcinated at a temperature of about 3100 F 1704 C dolomite breaks down to MgO and CaO and it is limited to about 3000 F 1649 C as a refractory. Calcined dolomite used in Germany as a water-filter material under the name of magno masse is in grain sizes to in to mm . Dolomite for the production of magnesia some of which is cut as building marble contains 10 to 20 magnesia 27 to 33 lime 1 to 12 alumina 40 to 46 carbonic acid 1 to 5 silica and 0 to 3 iron oxide. The dolomite found in huge deposits in Oklahoma contains CaO MgO and only very small amounts of silica alumina and iron oxide. For the production of magnesium metal calcined dolomite and ferrosilicon are brought to a high temperature in a vacuum and the magnesium is driven off as a vapor. In the ceramic industry dolomite is sometimes called bitter spar and rhombic spar. Isostatic pressing and sintering a mixture of like amounts of dolomite and synthesized zirconia plus by weight lithium fluoride yields a ceramic having a melting point of 3722 F 2050 C and 30 to 60 porosity that may be useful as a catalyst carrier for treating vehicle emissions. Developed by the National Industrial Research Institute of Nagoya in Japan porosity is controlled by varying the sintering temperature between 1832 and 2552 F 1000 and 1400 C . Nanoceramics of this composition could be used for high-temperature filters. DOUGLAS FIR. The wood of the tree Pseudotsuga taxifolia of the northwestern United States and British Columbia. It is sometimes called Oregon pine Douglas pine Douglas spruce red fir fir yellow fir and Puget Sound pine. The wood of young trees with wide growth rings is reddish brown and is the type .
