Enhanced Acid/Base Catalysis in High Temperature Liquid Water

Two novel and environmentally benign solvent systems, organic acids-ennchea high temperature liquid water （HTLW） and NH3-enriched HTLW, were developed, which can enhance the reaction rate of acid/base-catalyzed organic reactions in HTLW. We investigated the decomposition of fructose in organic acids-enriched HTLW, hydrolysis of cinnamaldehyde and aldol condensation of phenylaldehyde with acetaldehyde in NH3-enriched HTLW. The experimental results demonstrated that organic acids-enriched or NH3-enriched HTLW can greatly accelerate acid/base-catalyzed organic reactions in HTLW.

INCONSECUTIVE “SANDWICH STRUCTURE” PATTERN FOR HIGH TEMPERATURE WARM WATER IN THE WESTERN PACIFIC WARM POOL

An inconsecutive high frequency distribution with a"sandwich structure"pattern for high temperature warm water warmer than 29℃ in the western Pacific warm pool(WPWP) was found using Tropical Rainfall Measuring Mission(TRMM) sea surface temperature(SST) data,a relatively high resolution data for space.This phenomenon only shows up in boreal summer(June to September),and becomes obvious when WPWP SST is higher than 29℃.As observed,East Asian summer monsoon(EASM) impinges on Philippine Islands in July,which has an important impact on the formation and maintenance of the "sandwich structure".Winds affect the distribution of SST in two ways:one by increasing the local latent heat flux and the other by transporting cold water towards the southeast of Philippine Islands.

Fretting wear behavior of Zr alloy cladding tube mated with Zr alloy dimple under mixed fretting regime in simulated primary water of PWR

The fretting wear behavior of Zr alloy cladding tube under mixed fretting regime in a high-temperature pressurized water was investigated.The main wear mechanism is adhesive wear,with characters of small-scale delamination at the center of worn area and serious delamination on the worn edge.A long crack throughout the worn area and other cracks propagated towards the substrate are observed.The cross-sectional microstructure of worn area can be divided into a thick third-body layer,thin inner oxide layer and thick tribologically transformed structure layer,and their formation mechanisms are analyzed in detail.Finally,the mixed fretting regime process and the microstructural evolution during fretting wear are discussed.

Microstructure and intergranular stress corrosion cracking susceptibility of a SA508-52M-316L dissimilar metal weld joint in primary water

Correlation of microstructure and intergranular stress corrosion cracking （IGSCC） susceptibility for the SA508-52M-316L dissimilar metal weld joint in primary water was investigated by the interrupted slow strain rate tension test following a microstructure characterization. The susceptibility to IGSCC in var- ious regions of the dissimilar metal weld joint was observed to follow the order of Alloy 52 Mb〉 the heat affected zone of 316L〉 the dilution zone of Alloy 52 Mw〉 Alloy 52 Mw weld metal. The chromium- depletion at the grain boundary is the dominant factor causing the high IGSCC susceptibility of Alloy 52 Mh. However, IGSCC initiation in the heat affected zone of 316L is attributed to the increase of resid- ual strain adjacent to the grain boundary. In addition, the decrease of chromium content and increase of residual strain adjacent to the grain boundary increase the IGSCC susceptibility of the dilution zone of Alloy 52 Mw.

Crack Initiation Mechanism of Z3CN20.09M Duplex Stainless Steel during Corrosion Fatigue in Water and Air at 290 °C

The crack initiation mechanism of a Z3CN20.09M duplex stainless steel （DSS） during corrosion fatigue （CF） in water and air at 290 ℃ was investigated by using a CF cracking machine and a scanning electron microscopy （SEM）. The cracks were initiated successively at the persistent stip bands （PSBs）, phase boundaries （PBs） and pitting corrosion points （PCPs） of the specimens when they were tested in water at 290 ℃, while in airat 290 ℃ the cracks were only initiated at the PSBs and PBs. And the cracks were found mainly to initiate at the PSBs and PBs when the specimens were tested in water and air at 290 ℃, respectively. The results also reveal that the cracks were likely to be initiated at the first 20% of fatigue life of the specimens tested in water at 290 ℃. However, the cracks were not found until 50% of fatigue life when tested in air at 290 ℃. Moreover, the crack numbers of the specimens tested in water at 290 ℃ were much more than those tested in air at 290 ℃.

Effect of thermal ageing and dissolved gas on corrosion of 308L stainless steel weld metal in simulated PWR primary water

The corrosion of unaged and 7000-h thermally aged 308 L stainless steel weld metals in simulated PWR primary water under aerated and deaerated conditions was investigated,involving the corrosion of austenite,δ-ferrite andδ-ferrite/austenite phase boundary.The results revealed that thermal ageing for 7000 h had a limited effect on the corrosion behavior of 308 L weld metal as it only increased the inner oxide thickness ofδ-ferrite slightly under the deaerated condition.No obvious corrosion enhancement of 308 L weld metal under the aerated condition was found compared to the deaerated condition regardless of the thermal ageing.Nevertheless,Cr-enrichment on the surface of oxide particles,dissolved regions at the metal/oxide interface and localized corrosion along theδ-ferrite/austenite phase boundary occurred under the aerated condition.

Characteristics of Oxidation and Oxygen Penetration of Alloy 690 in 600°C Aerated Supercritical Water

The oxide films formed on Alloy 690 exposed to 600 ℃ supercritical water were characterized using mass measurement, X-ray diffraction. Raman spectroscopy, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. It was found that the mass gain of the alloy in supercritical water decreased with increasing exposure time. The oxide films have a double-layer structure, with an inner layer rich in Cr and outer layer rich in Ni and Fe after short time and long time exposure. The penetration of the oxide along the grain boundaries was observed, and the penetration depth increased with increasing exposure time. The grain boundaries and voids are the short-path of oxygen diffusion into the metal.

Microstructure and corrosion behavior of the heat affected zone of a stainless steel 308L-316L weld joint

Microstructure of the heat affected zone （HAZ） of a 308L-316L stainless steel （SS） weld joint and its corrosion behavior in high temperature water were studied. Peak of the residual strain was observed to approach to the fusion boundary in the HAZ while the strain increased from the top to root areas of the HAZ. The root area of the HAZ shows a lower corrosion resistance in high temperature water than the top and middle areas of the HAZ. This is attributed to a higher level of residual strain in association with a higher density of tangled dislocations in the top area of the HAZ. The results suggest that the residual strain in the HAZ could also promote the SCC through its effect on corrosion, in addition to that on the local microstructure and mechanical property of the steel.

Mechanism of selective hydrolysis of alginates under hydrothermal conditions

Mechanisms of selective hydrolysis of alginates under hydrothermal conditions were investigated by comparing reactivities of sodium alginate(Na-ALG,960 ku)solutions and calcium alginate(Ca-ALG)gels as substrates.Under hydrothermal conditions(150°C),hydrolysis of Na-ALG gave product molecular weights of 223,66,26 and 17 ku while those of Ca-ALG gave product molecular weights of 340,102,45 and 31 ku for reaction times of 10,20,30 and 60 min,respectively.The ratios of mannuronic acid(M)to guluronic acid(G)varied only slightly(from 1.3 to 1.2)for Na-ALG over the range of reaction times at 150°C,while ratios(M/G)for Ca-ALG exhibited a remarkable decrease(from 1.1 to 0.8).Diad sequence of alginate products obtained for Na-ALG were 17%,23%,27%and 31%(GG);30%,32%,36%and 38%(MM);and 53%,46%,37%and 32%(GM+MG);while for Ca-ALG they were 18%,22%,24%and 33%(GG);26%,23%,26%and 18%(MM);and 56%,54%,50%and 48%(GM+MG).Reaction mechanisms are proposed for hydrolysis of alginate solutions and alginate gels under hydrothermal conditions;de-polymerization of alginates into monomers and monomeric sequences can be controlled not only by hydrothermal conditions,but also by varying the physical state(solution,gel)of the starting materials.