Boron-rich liquid

The two-phase boride/carbide layer described in item 1 extends downward by reaction as the boron-rich liquid below it is drawn into the porous boron carbide by capillary action. Boron and carbon rapidly diffuse through this thin B-rich liquid layer, causing the two-phase layer to thicken as the directed reaction proceeds. 

The densification of boron carbide using silicon or aluminum is difficult to obtain due to the high vapor pressures of liquid silicon or aluminum at reasonable sintering temperatures, and which may hinder densification due to the formation of degassing channels and entrapment of residual gas in the closed pores. Telle and Petzow [404, 405] have demonstrated the existence of a binary equilibrium between a Bi2(B,C,Si)3 solid solution and boron-rich liquid silicon above 1560 ° C, which might be beneficial... 

A B-rich liquid forms at the reaction interface with the B4C as a result of this temperature rise. The first B-rich liquid in the system outside of molten boron occurs at 2165°C from eutectic reaction of B4C, C, and ZrCl (l. On further local heating (T > 2220°C), a continuous B-rich liquid can form between pure boron and the eutectic liquid. The exact composition of the B-rich liquid is unknown, but it appears to lie somewhere within the triangle formed by B4C, C, and ZrB2. 

This chapter attempts to provide a critical review of the work carried out on alkaline fuel cell, which directly uses hydrogen rich liquid fuel and oxygen or air as an oxidant. The subjects covered are electrode materials, electrolyte, half-cell analysis and single cell performance in alkaline medium. Koscher et al. (2003) brought out elaborate review work on direct methanol alkaline fuel cell. Earlier Parsons et al. (1988) reviewed literature on anode electrode where, the oxidation of small organic molecules in acid as well as in alkaline conditions was considered. A review work on electro-oxidation of boron compounds was done by Morris et al. (1985). However, in this chapter use of three specific fuels, e.g., methanol, ethanol and sodium borohydride in alkaline fuel cell is discussed. 

Since the vapor pressure of B2O3 is low (10 N/m at 1000°C), liquid B2O3 is deposited on the Si surface. If the initial partial pressure of BBrs is kept low enough, formation of a boron skin (SiB. or SiBg) on the Si wafers is avoided, and B-rich borosilicate glass is deposited instead. 

Reassessment of the Si-B system was based primarily on the model parameters given by Fries and Lukas [25], Modifications have been made on the thermodynamic properties of the liquid and solid diamond phases Experimental liquidus data reported by Brosset and Magunsson [26], Armas et al. [27], and Male and Salanoubat [28], solid solubility data reported by Trum-bore [18], Hesse [29], Samsonov and Sleptsov [30], and Taishi et al. [52], as well as the boron activities in liquid phase measured by Zaitsev et al. [32], Yoshikawa and Morita [33], Inoue et al. [7], and Noguchi et al. [31] were all used to determine the model parameters. Figure 13.4 shows the new assessed phase equilibria in the Si-rich Si-B system. 

The yields of aluminium and silicon are nearly constant for all the experiments, the yield of aluminium loeing slightly higher. The yield of incorporation of boron, instead, is very low when the synthesis gel is aluminium-rich (exp. -4). Boron and aluminium are incorporated at the same extent only when the available boron largely exceeds aluminium (exp. 5, 6). This behaviour can be accounted for by a competition between the Kinetics of incorporation of borosilicate and aluminosilicate units in the zeolite. No rate constants can be established without a knowledge of the partition coefficients of the elements between the liquid and solid phases of the synthesis gel. Anyway, the higher crystallization efficiency of the... 

Thermodynamic calculations by Dorner [78], Lukas [93] and Lim and Lukas [52], however, clearly demonstrated the existence of a binary phase equilibrium of boron carbide and a Si- and B-containing melt above 1560°C. The theoretical results were confirmed by hot pressing, liquid phase sintering and infiltration experiments by Lange and Holleck [75], Telle [83], Telle and Petzow [94], and Telle [54], which also yielded more details on the extension of the homogeneity field of boron carbide towards the Si-rich corner of the system B-C-Si. 

Fulvio PF, Lee JS, Mayes RT, Wang X, Mahurin SM, Dai S (2011) Boron and nitrogen-rich carbons from ionic liquid precursors with tailorable surface properties. Phys Chem Chem Phys 13 13486-13491... 

The in situ preparation of aryl and heteroaryl azides from the corresponding aryl halides via L-proline-promoted Cnl-catalyzed coupling reactions in the presence of alkynes allows the one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles (e.g. 226). Liang et al. also reported the one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles (e.g. 227) from aryl bromides or iodides and terminal alkynes in the presence of sodium azide using diamine-promoted Cnl-catalyzed reactions. It has also been shown that this type of synthesis can be carried out in a mixture of the ionic liquid [bmim][BF4] and water (Scheme 3.32). Starting with boronic acids, the catalytic approach to aryl azides and l-aryl-1,2,3-triazoles can be carried out under milder reaction conditions and improved substrate tolerance (Scheme 3.33). In fact, it was demonstrated that both electron-rich and electron-poor aryl boronic acids 228 could be efficiently converted into the corresponding aryl azides (229) in the presence of sodium azide and CUSO4. A one-pot protocol... 

Then, HgCdTe is grown via liquid phase epitaxy (LPE) from Te rich solution. The detector junctions are formed by boron ion implantation and then passivated by ZnS. The detectors are on 40 fim pitdi. Due to lateral diihi-sion, the fill factor is >90%. Typically six arrays are processed on the 2 in. and 21 arrays on the 3 in. wafers. A constant contour thickness map of a 3 in. PACE-I wafer is shown Fig. 1. The uniformity is excellent with the thickness being 13 /ttm 1.6 fan. across the area where arrays will be processed. The detectors are illuminated firom the backside, through the sapphire which can transmit up to 6.5 /on for 7 mil thidcness. However, a cutoff of 2.5 fjon is used for typical astronomy applications and 5 fan for high background applications. 

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