Abnormal grain growth of WC with small amount of cobalt

Li, T.; Li, Q.; Li, Lu; Fuh, Jerry Ying Hsi; Yu, Poh Ching

doi:10.1080/14786430701694309

Cited by 23 publications

(11 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A hypsochromic shift of 10-15 nm was observed in the UV spectrum of flavanonol, indicating that it has no free hydroxyl group at C-5. 16 In the (1). However, the two compounds had different retention times in HPLC analysis: t R1 D 13.18 min; t R6 D 15.81 min, suggesting that 6 was an isomer of DHM.…”

Section: Resultsmentioning

confidence: 84%

“…Also, dihydromyricetin (DHM, 1), namely ampelopsin, is a major constituent of A. grossedentata, and it constitutes about 20-30% (w/w) in the dry tender stems and leaves of the plant. 1,2 Recently, the biological activities of DHM have been observed, including hypoglycemic, 3,4 antioxidation, 5,6 antibacterial 7,8 and hepatoprotective activities. 9,10 Our pharmacological results indicated that after DHM was administered orally to rats, the serum of the rats had the activities of proliferation of isletˇ-cells and secretion of insulin.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Isolation and identification of metabolites from dihydromyricetin

Zhang

Que

Yang

et al. 2007

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

Dihydromyricetin (DHM) is the major bioactive constituent of Rattan Tea, which is the tender stems and leaves of Ampelopsis grossendentata. Seven metabolites (2-8) of DHM (1) were obtained by the chromatographic method. The metabolites 2-5 were obtained from the urine of rats administered orally with DHM; and metabolites 6-8 were detected in the fecal specimens of rats, which were also produced by human intestinal bacteria (HIB) in vitro, and were separated from the cultured media of HIB containing DHM. Their structures were elucidated as 5,7,3',5'-tetrahydroxyflavanonol (2); 5,7,3',5'-tetrahydroxy-4'-methoxyflavanonol (3); 5,7,4',5'-tetrahydroxy-3'-methoxyflavanonol (4); and dihydromyricetin-O-5-beta-D-glucuronide (5); (2R,3S)-5,7,3',4',5'-pentahydroxyflavanonol (6); 3,4,5,7,3',4',5'-hepthydroxyflavan (7) and 5,7,3',4',5'-pentahydroxyflavanone (8) on the basis of UV, NMR and LC-MS/MS data. These seven metabolites were formed through familiar metabolic reactions. Dihydromyricetin-O-5-beta-D-glucuronide (5) is a new compound. The (13)C-NMR data of (2) and (4) are reported for the first time.

show abstract

Section: Resultsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Isolation and identification of metabolites from dihydromyricetin

Zhang

Que

Yang

et al. 2007

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

show abstract

“…21 shows a high magnification FE-SEM micrograph of a compact interrupted at 1073 K and also the initial powder, which shows a composite phase consisting of both individual particles and clusters of connected particles that have undergone necking. The clusters are hard agglomerates that persist even after the application of external pressure (40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50).…”

Section: Influence Of Agglomerationmentioning

confidence: 99%

“…11) showed a bimodal grain size distribution in the surface with the peaks at ≈700 nm and 1500 nm, while in the interior, the grain size distribution was also bimodal but with the two peaks at ≈250 nm and 480 nm. The bimodal size distribution arises because of abnormal grain growth (AGG) -a characteristic trait of the carbides that exhibit facetted grain boundaries [Li et al, 2007, Byung-Kwon Yoon et al, 2005. It is also interesting to note that the average grain size of both the normal and abnormal grains is higher on the surface than in the interior.…”

Section: Microstructure Analysismentioning

confidence: 99%

Spark Plasma Sintering of Ultrafine WC Powders: A Combined Kinetic and Microstructural Study

Kumar¹,

Kurokawa²

2012

Tungsten Carbide - Processing and Applications

View full text Add to dashboard Cite

“…Shape changes accompanying grain growth in the dual phase hexagonal carbides (WC-Co, WC-Ni and even pure WC) are usually attributed to the strong difference in surface energies between the prismatic and basal planes which subsequently lead to angular and faceted grains [4]. Secondary recrystallization or abnormal grain growth (AGG) is suspected to be a consequence of surface ledges produced by screw dislocations, stacking faults or twin defects on specific crystal planes which act as 2D nucleation sites for growth at later stages [5,6].…”

Section: Introductionmentioning

confidence: 99%

The influence of Si on the microstructure and sintering behavior of ultrafine WC

Kumar

Watabe

Kurokawa

2012

Philosophical Magazine

View full text Add to dashboard Cite

The microstructure of sintered nano scale tungsten carbide powders with 1wt. % Si addition was found to be populated by an abnormally large number of elongated grains. Interrupted sintering experiments were conducted to clarify the origins of the excessive abnormal grain growth seen in the microstructure. It was observed that rapid coarsening occurred at high temperatures owing to the formation of a liquid phase. However, the grain shape evolution during this coarsening period was found to be a consequence of excessive stacking faults and micro twins on the basal planes probably generated by reaction of WC with Si. Analyses of the microstructures and the isothermal and non isothermal coarsening behaviors suggested that the platelet morphology evolved by defect-assisted nucleation and growth on faceted grains. Based on experimental evidence from samples interrupted at low temperatures and crystal growth theories, we discuss the possible mechanisms that eventually led to the rampant platelet-type morphology. Further, the influence of such rapid grain growth on the shrinkage rate during sintering is also discussed. In comparison with the cyclic coarsening-densification process of sintering in pure nano scale WC, the addition of Si leads to only two distinct sintering stages: either densification dominated or coarsening dominated. Concurrent densification and coarsening cannot be sustained particularly in the presence of a liquid phase that significantly enhances coarsening.

show abstract

Abnormal grain growth of WC with small amount of cobalt

Cited by 23 publications

References 33 publications

Isolation and identification of metabolites from dihydromyricetin

Isolation and identification of metabolites from dihydromyricetin

Spark Plasma Sintering of Ultrafine WC Powders: A Combined Kinetic and Microstructural Study

The influence of Si on the microstructure and sintering behavior of ultrafine WC

Contact Info

Product

Resources

About