Alumina modulus

AR = alumina ratio (alumina modulus). ASR = alkali silica reaction. LSF = lime saturation factor. SR = silica ratio (silica modulus). C, = analytical (total) concentration of x, irrespective of species, [x] = concentration of species x. x = activity of species x. RH = relative humidity. =... 

The alumina modulus is the ratio of alumina to iron oxide. If the alumina modulus is 0.637 or less, no tricalcium silicate in formed in the melt phase. 

Ferrite microscopy was the subject of a paper in 1967 by Ono and Shimota. Various crystallographic and optical properties of ferrite were described as a function of the aluminum to (aluminum + iron) ratio, the alumina modulus, in laboratory-produced clinkers. 

Relatively low CjS content and high periclase improved crystallinity of CjA unsoundness at MgO of 4.0% with CjA greater than 7% Effects of slow cooling in laboratory test. Suggested remedy is to lower alumina modulus and increase fineness of cement (Chopra and others, 1982)... 

Gaidzhurov, P.P. et al. (1994) Effect of the alumina modulus and 3rd transition metal oxides on properties of white Portland cement (in Russian). Izvestiya Vysshikh Uchebnykh Zavedenii, Khimiya I Khimicheskaya Tekhnologiya 31,102-106 [ref CA 120/225155]. 

Alumina modulus— the ratio AM=Al203/Fc2O3 in a Portland cement raw meal or clinker. 

Fig. 18 Relative compressive strengths associated with variation of the silica modulus (laboratory cements referred to cement with lime standard KSt I = 95 silica modulus 2.0 alumina modulus 2.0 2.8% SO3 fineness 3200cm /g Blaine)...

Fig. 8 Effect of limestone particle size on free CaO content at various burning temperatures (from Lehman/Locher/Thormann, 1964) dp — average particle size of a fraction lime standard KStI = 96 silica modulus = 3.0 alumina modulus = 2.2 At/At = 5to K/min. t = 30min. clay component illite...

Fig. 11. Modulus inciease as a function of fibei volume fraction alumina fiber-reinforced aluminum—lithium alloy matrix for (a) E (elastic modulus),...

There are, of course, many more ceramics available than those listed here alumina is available in many densities, silicon carbide in many qualities. As before, the structure-insensitive properties (density, modulus and melting point) depend little on quality -they do not vary by more than 10%. But the structure-sensitive properties (fracture toughness, modulus of rupture and some thermal properties including expansion) are much more variable. For these, it is essential to consult manufacturers data sheets or conduct your own tests. 

Fillers. Addition of fillers is not common in polychloroprene latex formulations. Fillers are used to reduce cost and control rheology, solids content and modulus. However, cohesion and adhesion are reduced. Calcium carbonate, clay and silica are some of the fillers than can be added. Alumina trihydrate is often used when resistance to degradation by flame is important. 

Recently, Oldfield Ellis (1991) have examined the reinforcement of glass-ionomer cement with alumina (Safil) and carbon fibres. The introduction of only small amounts of carbon fibres (5% to 7-5% by volume) into cements based on MP4 and G-338 glasses was found to increase considerably both the elastic modulus and flexural strength. There was an increase in work of fracture attributable to fibre pull-out. A modulus as high as 12-5 GPa has been attained with the addition of 12% by voliune of fibre into MP4 glass (Bailey et al, 1991). Results using alumina fibre were less promising as there was no fibre pull-out because of the brittle nature of alumina fibres which fractured under load. 

Silica Brick. Under ASTM C416, types A and B silica bricks are classified according to chemical composition and strength. Silica brick must have an average modulus of rupture of 3.5 MPa (500 psi), <1.5% A O no more than 0.2% Ti02, <2.50% Fe203, and <4.00% CaO. Type A brick must have a flux factor <0.5. The flux factor is equal to the percent alumina plus twice the percent of alkalies. Type B are all other silica brick covered by the standard chemical and strength specifications. 

To balance some of the drawbacks produced by the rubber toughening of thermosets, inorganic fillers that increase modulus and yield stress can be added to generate hybrid composites. Inorganic fillers such as glass beads, alumina, or silica - with high values of modulus and strength - are frequently included in thermoset formulations. 

LGMs of the AT/alumina and AT/ZTA displayed some very interesting properties which include excellent machinability, low thermal expansion coefficient, improved thermal shock resistance, low hardness (about 5 GPa), low Young s modulus (E) (250 GPa) and excellent flaw tolerance [Pratapa, 1997 Pratapa Low, 1998 Skala, 2000 Manurung, 2001], These materials appeared to display a large degree of near-surface quasi-plasticity under the Hertzian or the Vickers indenter which effectively inhibits the formation and propagation of cracks. The ductile behaviour of these materials was... 

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