Preparation and mechanisms of cemented carbides with ultrahigh fracture strength

2015 ◽  
Vol 48 (4) ◽  
pp. 1254-1263 ◽  
Author(s):  
Xingwei Liu ◽  
Xiaoyan Song ◽  
Haibin Wang ◽  
Xuemei Liu ◽  
Xilong Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Fracture Strength ◽  
Growth Inhibitor ◽  
Mean Value ◽  
Crystallographic Analysis ◽  
Cemented Carbides ◽  
Composite Powders ◽  
Grain Growth Inhibitor ◽  
Carbon Concentrations

WC–Co cemented carbides were prepared by liquid-state sintering ofin situsynthesized composite powders with a constant Co content but different carbon concentrations, and with different size scales of VC particles as grain-growth inhibitor. With an optimized carbon addition and doping with microscale VC particles, an ultrahigh fracture strength with a mean value above 5000 MPa was achieved for cemented carbides. By detailed crystallographic analysis of the configuration and interactions of the WC, Co and VC phases, the effects of VC particle size on the microstructure and mechanical properties of cemented carbides are identified. The mechanisms by which the fracture strength depends on the VC particle size contain the effects on the changes in Co binder distribution, atomic matching at the phase boundary and WC grain size. The dominant factors for ultrahigh fracture strength of cemented carbides are proposed.

Synthesis, characterization and formation mechanism of Ta–W nanocrystalline composite powders fabricated by nano-in situ composite method

RSC Advances ◽  
2016 ◽  
Vol 6 (107) ◽  
pp. 106011-106018 ◽  
Author(s):  
Yubo Chen ◽  
Jinglian Fan ◽  
Haoran Gong ◽  
Fensheng Zou ◽  
Yongzhong Guo ◽  
...  
Keyword(s):  
Particle Size ◽  
Oxygen Content ◽  
Formation Mechanism ◽  
Low Oxygen ◽  
Composite Powders ◽  
In Situ Composite ◽  
Nanocrystalline Composite ◽  
Nanocomposite Powders ◽  
Uniform Particle Size

To overcome the challenges involved in fabricating Ta–W nanocomposite powders using traditional methods, a novel process of preparing Ta–W nanocrystalline composite powders with a uniform particle size and low oxygen content is proposed herein.

Enhanced electrochemical performances of LiFePO4-C synthesized with PEG as the grain growth inhibitor for Li-ion capacitors in LiNO3 aqueous electrolyte

2017 ◽  
Vol 46 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Shen Qiu ◽  
Xugang Zhang ◽  
Yawen Li ◽  
Ting Sun ◽  
Chenlong Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Aqueous Electrolyte ◽  
Low Cost ◽  
Growth Inhibitor ◽  
Positive Electrode ◽  
Electrochemical Performances ◽  
Environment Friendly ◽  
Content Type ◽  
Grain Growth Inhibitor ◽  
Positive Electrode Material

Purpose The purpose of this paper is to conduct the synthesization of LiFePO4-C (LFP-C) with fine particle size and enhanced electrochemical performance as the positive electrode material for Li-ion capacitors (LICs) with neutral aqueous electrolyte. Design/methodology/approach LFP-C was prepared by using polyethylene glycol (PEG) as a grain growth inhibitor, and the effects of the calcination temperature and PEG content on the structure and morphology of LFP-C were investigated. LICs using environment-friendly, safe and low-cost LiNO3 aqueous electrolyte were assembled with LFP-C as the positive electrode and active carbon as the negative electrode. The electrochemical performances of LFP-C and LICs were studied. Findings The results show that the particle size of LFP-C decreases significantly through the introduction of PEG. Cyclic voltammetry results show that the LFP-C prepared at 550°C with 1.0 g PEG exhibits the highest Cpe of 725 F/g at the scanning rate of 5 mA/s. Compared to LFP prepared without PEG, the electrochemical performance of optimized LFP-C dramatically increases due to the decrease of the particle size. Moreover, the LIC assembled with the optimized LFP-C exhibits excellent electrochemical performances. The LIC maintains about 91.3 per cent of its initial Cps after 200 cycles which shows a good cycling performance. Research limitations/implications The LFP-C is the suitable positive electrode material for LICs with neutral aqueous electrolyte. LICs can be used in the field of automobiles and can solve the problems of energy shortage and environmental pollution. Originality/value Both the LFP-C with fine particle size and its optimal LIC using environment-friendly, safe and low-cost LiNO3 aqueous electrolyte own good electrochemical performances.

Analysis of Microgram Tungsten Carbide-Cobalt Cemented Carbides

1976 ◽  
Vol 34 ◽  
pp. 624-625
Author(s):  
T.A. Emma
Keyword(s):  
Grain Growth ◽  
High Hardness ◽  
Growth Inhibitor ◽  
High Strength ◽  
Cemented Carbides ◽  
Grain Growth Inhibitor ◽  
Concentrated Sulfuric Acid ◽  
Grain Size And Shape ◽  
Co Alloys ◽  
Sintered Product

When small quantities of a grain growth inhibitor are added to starting powders containing submicron WC and Co, the sintered product is a high strength, high hardness alloy. The microstructure of the carbide is quite similar to that of the macrograin variety. For the purposes of this study WC with 10-20% Co alloys containing small amounts of a grain growth inhibitor were examined with the electron microscope to determine grain size and shape, general composition, identification of possible undesirable species, and the disposition of the grain growth inhibitor.During the initial stages of the investigation, fractured surfaces were examined using an RCA-3F microscope converted to operate as a high resolution diffraction instrument with 50 cm camera. Reflection patterns from fractured surfaces showed that the major phase was cobalt with a weaker pattern from WC, indicating that fracture took place inside the cobalt cement. These same surfaces were then treated electrolytically in concentrated sulfuric acid at a temperature in the range between 3 and 8°C to remove the cobalt binder.

Effect of VC, TaC and NbC Additions on Microstructure and Properties of Ultrafine WC-10%Co Cemented Carbides

2013 ◽  
Vol 320 ◽  
pp. 281-286 ◽  
Author(s):  
Hao Yu ◽  
Wan Ni Li ◽  
Xian Quan Jiang ◽  
Peng He Jiao
Keyword(s):  
Mechanical Properties ◽  
Grain Growth ◽  
Growth Inhibitor ◽  
Cemented Carbides ◽  
Testing Methods ◽  
Vacuum Sintering ◽  
Microstructure And Properties ◽  
Grain Growth Inhibitor

The ultrafine WC-10%Co cemented carbides were prepared by vacuum sintering processing. To inhibit the growth of WC grains during sintering, single VC, TaC and NbC were used as inhibitors. Effects of VC, TaC and NbC as grain growth inhibitor on the microstructure and properties of ultrafine WC-10%Co cemented carbides were investigated with different kinds of testing methods. With the transformation of doped inhibitors content, the results show that VC, TaC and NbC additions can refine the WC grains, and increase the mechanical properties of the WC-10%Co cemented carbides, respectively. And the efficiency of these three kinds of inhibitors to limit gain size has been compared after sintering for 1.5h at 1 400 °C.

Novel Formulation Development and Evaluation of Nanoparticles Based in Situ Gelling System for The Ophthalmic Delivery of Ciprofloxacin Hydrochloride

2015 ◽  
Vol 5 (4) ◽  
Author(s):  
Kranti Singh ◽  
Surajpal Verma ◽  
Shyam Prasad ◽  
Indu Bala
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Drug Loading ◽  
In Vitro Release ◽  
Formulation Development ◽  
Ciprofloxacin Hydrochloride ◽  
Potential Value ◽  
The Mean ◽  
In Situ Gelling

Ciprofloxacin hydrochloride loaded Eudragit RS100 nanoparticles were prepared by using w/o/w emulsification (multiple emulsification) solvent evaporation followed by drying of nanoparticles at 50°C. The nanoparticles were further incorporated into the pH-triggered in situ gel forming system which was prepared using Carbopol 940 in combination with HPMC as viscosifying agent. The developed nanoparticles was evaluated for particle size, zeta potential value and loading efficiency; nanoparticle incorporated in situ gelling system was evaluated for pH, clarity, gelling strength, rheological studies, in-vitro release studies and ex-vivo precorneal permeation studies. The nanopaticle showed the mean particle size varying between 263.5nm - 325.9 nm with the mean zeta potential value of -5.91 mV to -8.13 mV and drug loading capacity varied individually between 72.50% to 98.70% w/w. The formulation was clear with no suspended particles, showed good gelling properties. The gelling was quick and remained for longer time period. The developed formulation was therapeutically efficacious, stable and non-irritant. It provided the sustained release of drug over a period of 8-10 hours.

scholarly journals Effect of bimodal WC particle size and binder composition on the morphology of WC grains in WC–Co–Ni3Al cemented carbides

2021 ◽  
Vol 12 ◽  
pp. 1747-1754
Author(s):  
Yingbiao Peng ◽  
Tao Li ◽  
Jianzhan Long ◽  
Haohan Li ◽  
Bizhi Lu ◽  
...  
Keyword(s):  
Particle Size ◽  
Cemented Carbides ◽  
Binder Composition

Effect of particle size on in-situ desulfurization for oxy-fuel CFBC

Fuel ◽  
2021 ◽  
Vol 291 ◽  
pp. 120270
Author(s):  
Seo Yeong Kang ◽  
Su Been Seo ◽  
Eun Sol Go ◽  
Hyung Woo Kim ◽  
Sang In Keel ◽  
...  
Keyword(s):  
Particle Size ◽  
Effect Of Particle Size

scholarly journals Effects of processing, moisture, and storage length on the fermentation profile, particle size, and ruminal disappearance of reconstituted corn grain

2020 ◽  
Vol 98 (11) ◽  
Author(s):  
Ana L M Gomes ◽  
Antonio V I Bueno ◽  
Fernando A Jacovaci ◽  
Guilherme Donadel ◽  
Luiz F Ferraretto ◽  
...  
Keyword(s):  
Particle Size ◽  
Lactic Acid ◽  
Butyric Acid ◽  
Hammer Mill ◽  
Moisture Concentration ◽  
Fermentation Profile ◽  
And Storage ◽  
Ground Corn ◽  
Corn Grain

Abstract Our objective was to examine the effects of processing, moisture, and anaerobic storage length of reconstituted corn grain (RCG) on the fermentation profile, geometric mean particle size (GMPS), and ruminal dry matter disappearance (DMD). Dry corn kernels were ground (hammer mill, 5-mm screen) or rolled, then rehydrated to 30%, 35%, or 40% moisture, and stored for 0, 14, 30, 60, 90, 120, or 180 d in laboratory silos. Rolled corn had an increased GMPS compared with ground corn (2.24 and 1.13 mm, respectively, at ensiling). However, there was a trend for an interaction between processing and moisture concentration to affect particle size, with GMPS increasing with increased moisture concentration, especially in ground corn. Longer storage periods also slightly increased GMPS. Processing, moisture, and storage length interacted to affect the fermentation pattern (two- or three-way interactions). Overall, pH decreased, whereas lactic acid, acetic acid, ethanol, and NH3-N increased with storage length. RCG with 30% moisture had less lactic acid than corn with 35% and 40% moisture, indicating that fermentation might have been curtailed and also due to the clostridial fermentation that converts lactic acid to butyric acid. Ensiling reconstituted ground corn with 30% of moisture led to greater concentrations of ethanol and butyric acid, resulting in greater DM loss than grain rehydrated to 35% or 40% of moisture. Ammonia-N and in situ ruminal DMD were highest for reconstituted ground corn with 35% or 40% of moisture, mainly after 60 d of storage. Therefore, longer storage periods and greater moisture contents did not offset the negative effect of greater particle size on the in situ ruminal DMD of rolled RCG. Nonetheless, RCG should be ensiled with more than 30% moisture and stored for at least 2 mo to improve the ruminal DMD and reduce the formation of ethanol and butyric acid.

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