Investigation of characteristics and properties of spark plasma sintered ultrafine WC-6.4Fe3.6Ni alloy as potential alternative WC-Co hard metals

Author(s):  
Erijanio Nonato da Silva ◽  
Alessandra Agna Araújo dos Santos ◽  
Rubens Maribondo do Nascimento ◽  
Salete Martins Alves ◽  
Renan da Silva Guimarães ◽  
...  
2017 ◽  
Vol 899 ◽  
pp. 487-492
Author(s):  
Luis Antonio C. Ybarra ◽  
Afonso Chimanski ◽  
Gilberto J. Pereira ◽  
Izabel Fernanda Machado ◽  
Humberto Naoyuki Yoshimura

Cobalt is widely used to produce WC-Co hard metals, but this binder has problems of shortage and unstable price. In this work, cobalt was replaced by an iron aluminide intermetallic binder. WC-10%(Fe3Al-3%B) composite was prepared by vibration milling of WC, Fe, Fe-B, and Al powders and sintered by spark plasma sintering (SPS) at 1150 °C for 8 min under 30 MPa. The milling time was 0.17, 12, 25 and 50 h. The SPS was efficient to consolidate the composite resulting in relative density of ~98% or higher. With increasing milling time, Vickers hardness (HV30) of composite increased from 12 to 14 GPa due to the enhanced homogeneity of microstructure, while the fracture toughness, KIc, determined by an indention fracture method using Shetty equation, remained constant at around 9.1 MPa.m1/2.


2013 ◽  
Vol 376 ◽  
pp. 38-41 ◽  
Author(s):  
Nikoloz Jalabadze ◽  
Lili Nadaraia ◽  
Levan Khundadze

Due the rapid heating rate combined with high pressure by the Spark Plasma Sintering (SPS) technologies possible manufacture a wide range of novel materials with exceptional properties that cannot be achieved using conventional sintering techniques. Hard metals are, from a technical point of view, one of the most successful composite materials. An overview of the metallurgical reactions during the SPS sintering process of powder mixtures for the manufacture of hard metals is presented. The relatively complex phase reactions in the multi-component system TiC-Mo-W-Ni are discussed. There were elaborated a new technology for the fabrication of nanocrystalline hard metals of a new class assigned for the production of articles with high different characteristics. Elaborated materials are characterized by high melting temperature, hardness, wear-resistance, and satisfactory strength at high temperature and corrosive resistance. Through the use of developed technology and the appropriate structural condition gives possibility to achieve high physical-mechanical characteristics. Obtaining of composite materials via elaborated technology is available from the corresponding complex compounds and directly consisting elements too. In this case High-temperature Self-propagation Synthesis (SHS) and spark plasma sintering/synthesis (SPS) process are united and during a single operation it is possible to get not only the powder materials but at the same time obtain required details.


1994 ◽  
Vol 71 (01) ◽  
pp. 129-133 ◽  
Author(s):  
P J Declerck ◽  
S Vanderschueren ◽  
J Billiet ◽  
H Moreau ◽  
D Collen

SummaryStreptokinase (SK) is a routinely used thrombolytic agent but it is immunogenic and allergenic; staphylokinase (STA) is a potential alternative agent which is under early clinical evaluation. The comparative prevalence of antibodies against recombinant STA (STAR) and against SK was studied in healthy subjects and their induction with intravenous administration in small groups of patients.Enzyme-linked immunosorbent assays, using microtiter plates coated with STAR or SK and calibration with affinospecific human antibodies, revealed 2.1 to 65 μg/ml (median 11 μg/ml) anti-STAR antibodies and 0.9 to 370 μg/ml (median 18 μg/ml) anti-SK antibodies (p <0.001 vs anti-STAR antibodies) in plasma from 100 blood donors, with corresponding values of 0.6 to 100 μg/ml (median 7.1 μg/ml) and 0.4 to 120 μg/ml (median 7.3 μg/ml), respectively, in 104 patients with angina pectoris. Three out of 17 patients with Staphylococcus aureus bacteremia had significantly increased anti-STAR antibody levels (150, 75 and 75 μg/ml), and STAR neutralizing activities (2.2, 3.6 and 4.1 μg STAR neutralized per ml plasma, respectively). In 6 patients with acute myocardial infarction, given 10 mg STAR intravenously over 30 min, median anti-STAR antibody levels were 3.5 μg/ml at baseline, 2.9 μg/ml at 6 to 8 days and 1.2 μg/ml at 2 to 9 weeks, with median corresponding titers of STAR neutralizing activity at 2 to 9 weeks of 42 μg/ml plasma. Conversely, in 5 patients treated with 1,500,000 units SK over 60 min, median anti-SK antibodies increased from 2.9 μg/ml at baseline to 360 μg/ml at 5 to 10 days, with corresponding median SK neutralizing activities of 13 μg/ml. Antibodies against STAR did not cross-react with SK and vice versa.Plasma from human subjects contains low levels of circulating antibodies against recombinant staphylokinase, and intravenous administration of this compound boosts antibody titers. These antibodies do however not cross-react with streptokinase, whereby the use of these two immunogenic thrombolytic agents would not be mutually exclusive.


2011 ◽  
Vol 49 (01) ◽  
pp. 40-45 ◽  
Author(s):  
Hyun-Kuk Park ◽  
Seung-Min Lee ◽  
Hee-Jun Youn ◽  
Ki-Sang Bang ◽  
Ik-Hyun Oh

2015 ◽  
Vol 30 (3) ◽  
pp. 267
Author(s):  
HUANG Lin-Yun ◽  
LI Chen-Hui ◽  
KE Wen-Ming ◽  
SHI Yu-Sheng ◽  
HE Zhi-Yong ◽  
...  

2017 ◽  
Vol 59 (11-12) ◽  
pp. 1033-1036 ◽  
Author(s):  
Sherzod Kurbanbekov ◽  
Mazhyn Skakov ◽  
Viktor Baklanov ◽  
Batyrzhan Karakozov

2012 ◽  
Vol 27 (9) ◽  
pp. 961-964 ◽  
Author(s):  
Zhi-Qiang MA ◽  
Ying-Hu JI ◽  
Lian-Jun WANG

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