Nickel sintering

Sol-gel technique has also been applied to modify the anode/electrolyte interface for SOFC running on hydrocarbon fuel [16]. ANiA SZ cermet anode was modified by coating with SDC sol within the pores of the anode. The surface modification of Ni/YSZ anode resulted in an increase of structural stability and enlargement of the TPB area, which can serve as a catalytic reaction site for oxidation of carbon or carbon monoxide. Consequently, the SDC coating on the pores of anode leads to higher stability of the cell in long-term operation due to the reduction of carbon deposition and nickel sintering. 

Chovil A, Sutherland RB, Halliday M. 1981. Respiratory cancer in a cohort of nickel sinter plant workers. Br J Ind Med 38 327-333. 

Muir DCF, Jadon N, Julian JA, et al. 1994. Cancer of the respiratory tract in nickel sinter plant workers effect of removal from sinter plant exposure. Occup Environ Med 51(1) 19-22. 

Performance Characteristics. The sintered nickel-sintered iron design battery has outstanding power characteristics at all states of discharge. making them attractive to the design of electric vehicles (EV) which must accelerate with traffic even when almost completely discharged. 

Transmission electron micrographs and XPS results have been used to show that a catalyst, with a high silica content in the matrix, prevents nickel dispersion (16,18). In fact, in a FCC with a Si-rich (Si/Al = 4.3) surface, XPS data has indicated that calcination and steaming cause nickel (and vanadium) migration to the cracking catalyst surface where nickel sinters. As a result, nickel crystallites 50... 

Perovskite materials show outstanding thermal and mechanical stability at temperatures typical for the performance of SOFCs in contrast with the standard Ni/YSZ cermet, where nickel sintering and agglomeration are latent risks [144],... 

The experimental evaporator (micro two-phase jets generator) is shown on Fig. 10 -11. The heater block of the evaporator includes a hole machined directly in the centre of the copper cylinder with thick walls and is used for the installation of a nickel sintered powder evaporator. Some thermocouples are disposed inside the copper block to control the heat flow to the evaporator from the electric heater disposed on its outer surface. To minimize heat losses, the heater block was insulated. Heat input to the evaporator was calculated by conduction analysis using thermocouples that were placed at a known distance apart in the copper heater block. 

The applicability of such models to the present case of nickel sintering at low temperature has been tested aiming at identifying the pertaining mechanism(s),... 

Composite membranes also employ dense cermets fabricated by sintering together mixed powders of metal and ceramic [10-12], Examples include powders of Pd and its alloys sintered with powders of perovskites [11,12], niobium sintered together with AI2O3 [12], and nickel sintered with proton-conducting perovskites. Layers of dense cermets, 25-100 xm thick, are supported by porous ceramic tubes. Cermets employing chemically reactive metals, Nb, Ta, U, V, Zr, and their alloys, are typically coated with Pd and alloys thereof [11,12],... 

The density of sulfur is close to that of lithium chloride. The volume of solid sulfur formed in reaction (11.9) is less than 16% of the overall volume of solid products. Sulfur dioxide formed in reaction (11.9) is rather soluble in electrolyte, so that the intrinsic pressure in the cells is enhanced negligibly. Despite this, the cases of thionyl chloride-lithium cells are made to be rather strong and the extreme corrosion activity of thionyl chloride enforces application of high-alloy steels or nickel. Sintered glass-metal pressure seals are used in thionyl chloride-lithium cells, same as in cells with some other systems. 

The melting temperature of nickel is 1726 K. Therefore, according to Equation 19.1, nickel sintering may be carried out above 517 K. 

Section Durability/ReliabUity of SOFC Systems describes durability/reliability of SOFC systems. Failures of system operation are first described. Then, failures of stacks and degradation of cell performances are described in detail with focuses on chromium poisoning, nickel sintering, carbon deposition, sulfur poisoning, etc. Results of field tests are also described in relation to reliability. Section Cost Issues describes the cost issue and Future Directions of SOFC development are given finally in section Future Directions. ... 

These features have been found to be highly correlated with the fabrication method/sequence as well as materials selected. For example, anode support cells have stable anodes but there remain several points to be optimized for a cathode-complex-layer structure. On contrary, cathode-support cells have the stable performance for cathodes, but anodes may have some changed in microstructure because of nickel sintering [63]. 

Because the anode reaction is relatively fast at MCFC temperatures, a high surface area anode catalyst is not required [13, 95, 111-114]. State-of-the-art anodes are made of a sintered Ni-Cr/Ni-Al alloy with a thickness of 0.4-0.8 mm and porosity of 55-75 %. Fabrication is carried out usually by tape casting a slurry of the powdered material, which is subsequently sintered. Chromium is added to the basic nickel component to reduce the nickel sintering that could give rise to a decay in the MCFC, performances. However, chromium can react with lithium of the electrolyte causing some loss of electrolyte. Addition of aluminum can improve both creep resistance in the anode and electrolyte loss due to the formation of LiA102 within the nickel particles. Ni-Cr/Ni-Al alloy are well established materials for the anodes, however nowadays the research is addressed to obtain new and less expensive materials. Moreover many efforts are addressed toward sulfur resistance materials such as LiFe02. 

Loading of active material Electrochemical impregnation gives very uniform loading of the active material within the pores of the nickel sinter. 

For most general purposes sintered bronze filters are suitable. For particularly arduous duties involving very high pressures, high temperatures or corrosive fluids the filter elements may be sintered from stainless steel. Monel, pure nickel, Hastelloy, titanium or even tungsten. Bronze and cupro-nickel sinter readily at low temperatures and thus a whole variety of shapes can be produced directly from metal powder in stainless steel or carbon moulds. The mould is passed through a furnace with a protective atmosphere to sinter the powder. Pressed or machined shapes may require subsequent treatment to open up surface pores. The elements can be machined to closer tolerances than can be produced by direct moulding, but... 

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