In-situ coagulation moulding of ceramic suspensions

A fast, near-net shape route for the production of advanced ceramic components has been developed in which the time dependent in-situ hydrolysis of carboxylic acid derivatives progressively destabilises a suspension within a non porous mould to form a viscoelastic green body solid within which the homogeneity of the initial dispersion is maintained. After drying, the ceramics could be sintered without needing debinding since <1 wt% of organic additives were used. As applied to a-alumina initially dispersed using ammonium polyacrylate, this new process route yielded dense, high strength, reliable components with uniform microstructures

Hydrolysis of carboxylic lactones in alumina slurries

The hydrolysis of three carboxylic lactones, -butyrolactone, d-gulonic -lactone, and (±)- -hydroxy -butyrolactone, has been investigated in water and electrosterically stabilised alumina slurries. The effect of the acidification behaviour on the viscosity of the alumina slurries due to coagulation has also been studied. It has been found that the reaction temperature has a more significant influence than lactone concentration on the hydrolysis and acidification rate and hence on the time before the slurry becomes sufficiently rigid to be self-supporting

In situ coagulation moulding: a new route for high quality, net-shape ceramics

A fast, near-net shape route for the production of advanced ceramic components has been developed that uses carboxylic acid derivatives as coagulants for electrosterically dispersed, high solids content ceramic suspensions. The time dependent in situ hydrolysis of the coagulant D-gulonic-g-lactone progressively destabilises the suspension to form a viscoelastic solid within which the homogeneity of the initial dispersion is maintained. Constraining this hydrolysis reaction within a non-porous mould leads to the formation of green bodies...

Variability of fire carbon emissions in equatorial Asia and its nonlinear sensitivity to El Niño

The large peatland carbon stocks in the land use change-affected areas of equatorial Asia are vulnerable to fire. Combining satellite observations of active fire, burned area, and atmospheric concentrations of combustion tracers with a Bayesian inversion, we estimated the amount and variability of fire carbon emissions in equatorial Asia over the period 1997-2015. Emissions in 2015 were of 0.51±0.17Pg carbon-less than half of the emissions from the previous 1997 extreme El Niño, explained by a less acute water deficit. Fire severity could be empirically hindcasted from the cumulative water deficit with a lead time of 1 to 2months. Based on CMIP5 climate projections and an exponential empirical relationship found between fire carbon emissions and water deficit, we infer a total fire carbon loss ranging from 12 to 25Pg by 2100 which is a significant positive feedback to climate warming