Effects of Nano-Al2O3 Additions on Microstructures and Properties of WC-8Co Hard Metals

To investigate the role of nano-Al2O3, WC–Al2O3–8wt%Co hard metals was mixed with 0-1.2 wt% nano-Al2O3 and prepared by conventional sintering (CS) for 2 h at 1440°C to see whether the addition of Al2O3 could improve densification behaviour, the microstructure and mechanical properties of the samples. The results showed that the use of Al2O3 nanoparticles as dispersions could reduce the porosity of WC-Co alloy and decrease the relative density; it could also inhibit the growth of the grains of WC-Co hardmetal to enhance the hardness and transverse rupture strength of the alloy in a proper range. The influence of Al2O3 content on the magnetic properties including coercive force and saturated magnetic intensity of the WC–Al2O3–8wt%Co hardmetals manifested the additive of nano-Al2O3 have effect on the WC grain growth inhibition and the formation of decarbonization phase in the alloy.

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Effects of Magnetic Powder Loading on Mechanical Properties and Magnetic Properties of Natural Rubber

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.45.1423 ◽

2006 ◽

Vol 45 ◽

pp. 1423-1428

Author(s):

Somsak Woramongconchai ◽

Chatchawan Lohitvisat ◽

Aree Wichainchai

Keyword(s):

Mechanical Properties ◽

Magnetic Properties ◽

Coercive Force ◽

Natural Rubber ◽

Barium Ferrite ◽

Maximum Energy ◽

Magnetic Powder ◽

Elongation At Break ◽

Maximum Energy Product ◽

Energy Product

The effect of magnetic powders and powders loading on magnetic properties and mechanical properties of magnetic rubbers were studied. The natural rubber with magnetic powders, Barium ferrite, Neodymium iron boron, were used as starting materials to prepare magnetic rubbers. Barium ferrite (BaO.6F2O3) powders had been sintered at 1285 oC for 30 hours to improve its crystal structure. The physical properties of magnetic rubbers, residual flux density (Br), coercive force (Hc), maximum energy product (BHmax), hardness and density, had a trend to increase as enhancing magnetic powders loading. However, some properties such as, intrinsic coercive force (Hci), tensile strength and elongation at break, had a trend to decrease when the magnetic powder loading was increased. Magnetic properties of the anisotropic type, sintered powders, were higher than isotropic type, non-sintered powders, except the Hci because anisotropic magnetic rubber indicated crystal orientation in the same direction.

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Effect of Nitrogen on the Mechanical Properties of Heat-Resisting Steel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.535-537.571 ◽

2012 ◽

Vol 535-537 ◽

pp. 571-575

Author(s):

Xiao Liu ◽

Long Mei Wang

Keyword(s):

Electron Microscopy ◽

Mechanical Properties ◽

Scanning Electron Microscopy ◽

Room Temperature ◽

Rupture Strength ◽

N Addition ◽

Creep Rupture Strength ◽

Test Steel ◽

Scanning Electron

In this paper, the effect of N addition on mechanical properties of 21Cr-11Ni austenitic heat-resisting stainless steel was investigated. Scanning electron microscopy was used to study the fracture surfaces in the steels. N in 21Cr–11Ni heat-resisting steel can play a role of stabling austenite and ensuring the structure and mechanical properties in high temperatures. Fracture is changed from cleavage to ductile fracture to 21Cr–11Ni heat-resisting steel, and the strength of test steel are improved at room temperature by adding N, the tensile strength is increased by 8.33%. And the creep rupture strength is improved. The fracture time of the steel containing 0.2% N is 3.2 times higher than the steel containing 0.14% N at 1144K.

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Effect of Cryogenic Treatment on the Performance of Ultrafine Cemented Carbide

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1015.181 ◽

2014 ◽

Vol 1015 ◽

pp. 181-184 ◽

Cited By ~ 1

Author(s):

Ai Min Jiang ◽

Xian Quan Jiang ◽

Rong Yu ◽

Rong Jie Yang

Keyword(s):

Magnetic Properties ◽

Coercive Force ◽

Rupture Strength ◽

Cryogenic Treatment ◽

Cemented Carbide ◽

Cemented Carbides ◽

Transverse Rupture Strength

The effect of cryogenic treatment on the mechanical and magnetic properties of WC–6% Co Ultrafine cemented carbides has been investigated in this paper. The results show that after the cryogenic treatment, the hardness slightly increases from 1750 to 1830, however, the transverse rupture strength decreases from 2510 MPa to 2480MPa. ,the magnetization decreased from 5.82% to 5.72%, decreasing 1.71%for 24 h, but the coercive force slightly increases and reaches the maximum of 24 kA/m for 2h.

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Addition of Nano-ZrO2 Effects on Microstructures and Properties of WC-8Co Hard Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.496.302 ◽

2012 ◽

Vol 496 ◽

pp. 302-305 ◽

Cited By ~ 1

Author(s):

Lan Sun

Keyword(s):

Mechanical Properties ◽

Phase Transition ◽

Fracture Toughness ◽

Relative Density ◽

Hard Alloys ◽

Densification Behavior ◽

Sintering Process ◽

Toughening Mechanism ◽

Hard Metals ◽

Conventional Sintering

This paper carries out the research on using the toughening mechanism of phase transition of ZrO2 to inhibit the WC grain and improve the toughness of the hard alloys. WC–ZrO2–8wt%Co hard metals was mixed with 0-2 wt% nano-ZrO2 and prepared by conventional sintering (CS) for 2 h at 1440oC to see whether the addition of ZrO2 could improve densification behavior, the microstructure and mechanical properties of the samples. Experimental results showed that the use of ZrO2 nanoparticles could decrease the relative density because of the worse wetting effects; it could also inhibit the growth of the grains of WC-Co hardmetal to enhance the hardness of the alloy. The fracture toughness of sample has an increasing tendency as a whole because of the phase transition during the sintering process.

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Effects of Al2O3 Nanoparticle on the Microstructure and Magnetic Properties of Co/Al2O3 Coatings Prepared by Composite Plating

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.51.131 ◽

2008 ◽

Vol 51 ◽

pp. 131-139 ◽

Cited By ~ 1

Author(s):

Sheng Chang Wang ◽

Chih Hsiung Tseng

Keyword(s):

Electron Microscopy ◽

Magnetic Properties ◽

Volume Fraction ◽

Composite Films ◽

Al2o3 Content ◽

Al2o3 Nanoparticles ◽

Composite Plating ◽

Transmission Electron ◽

Al2o3 Particles ◽

Hcp Structure

Nanocomposite Co/Al2O3 coatings were fabricated by composite electrodeposition. The nanosized Al2O3 particles were suspended in aqueous cobalt sulfamate solution and subsequently co-deposited on a Cu substrate. The samples were characterized by Scanning electron microscopy and Atomic force microscopy for determination of surface morphology. X-ray diffraction technique concomitant with Transmission electron microscopy were utilized to identify the phases and emanation of microstructure while magnetic properties of the Co/Al2O3 nanocomposite coatings were investigated by vibrating sample magnetometer. The results indicated that, the Al2O3 nanoparticles suspended in the plating solution acquired a positively charge due to the presence of Co ions. These positively charged Al2O3 particles drift towards the cathode by electrophoresis and are reduced by Co ions to form the Co/Al2O3 composite film. The Co grains in the films show hcp structure with (11 2 0) preferred orientation. The grain size and surface roughness of the Co/Al2O3 compositesis found to decrease with increasing Al2O3 volume fraction while the magnetization of the composite films decreases with increasing concentration of Al2O3 nanoparticles. However the coercivity of the coatings was found to increase with increasing Al2O3 content. It could be delineated from the TEM micrographs that the Al2O3 nanoparticles dispersed in the Co matrix inhibited the grain growth of Co matrix resulting in pinning of the magnetic domains due to which the coercivity of the composite layers was found to increase.

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Magnetic Properties of xCeO2â€¢(50 âˆ’ x) PbOâ€¢50B2O3 Glasses and Glass Ceramics

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v13i1.6785 ◽

2017 ◽

Vol 13 (1) ◽

pp. 4486-4494 ◽

Cited By ~ 1

Author(s):

G.El Damrawi ◽

F. Gharghar

Keyword(s):

Magnetic Properties ◽

Large Scale ◽

Glass Ceramics ◽

Magnetic Behavior ◽

Crystal Formation ◽

Dual Roles ◽

Effective Agent ◽

Ordered Structures ◽

Essential Change

Cerium oxide in borate glasses of composition xCeO2Â·(50 âˆ’ x)PbOÂ·50B2O3 plays an important role in changing both microstructure and magnetic behaviors of the system. The structural role of CeO2 as an effective agent for cluster and crystal formation in borate network is clearly evidenced by XRD technique. Both structure and size of well-formed cerium separated clusters have an effective influence on the structural properties. The cluster aggregations are documented to be found in different range ordered structures, intermediate and long range orders are the most structures in which cerium phases are involved. The nano-sized crystallized cerium species in lead borate phase are evidenced to have magnetic behavior. The criteria of building new specific borate phase enriched with cerium as ferrimagnetism has been found to keep the magnetization in large scale even at extremely high temperature. Treating the glass thermally or exposing it to an effective dose of ionized radiation is evidenced to have an essential change in magnetic properties. Thermal heat treatment for some of investigated materials is observed to play dual roles in the glass matrix. It can not only enhance alignment processes of the magnetic moment but also increases the capacity of the crystallite species in the magnetic phases. On the other hand, reverse processes are remarked under the effect of irradiation. The magnetization was found to be lowered, since several types of the trap centers which are regarded as defective states can be produced by effect of ionized radiation.

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