INFLUENCE OF THE COBALT CONTENT IN HOT-PRESSED CEMENTED CARBIDES ON THE DEPOSITION OF LOW-PRESSURE DIAMOND LAYERS

1989 ◽  
Vol 50 (C5) ◽  
pp. C5-169-C5-176
Author(s):  
R. HAUBNER ◽  
B. LUX
Keyword(s):  
Cobalt Content ◽  
Low Pressure ◽  
Cemented Carbides

Microstructure of Electro-Eroded Cemented Carbide Surfaces

1968 ◽  
Vol 26 ◽  
pp. 284-285
Author(s):  
V. N. Filimonenko ◽  
M. H. Richman ◽  
J. Gurland
Keyword(s):  
Surface Layer ◽  
Cobalt Content ◽  
Cemented Carbides ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Metallographic Examination ◽  
Standard Procedures ◽  
Face Centered ◽  
Diamond Paste ◽  
Plastic Carbon

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.

Focus on Carbide-Tipped Circular Saws when Cutting Stainless Steel and Special Alloys

2015 ◽  
Vol 1114 ◽  
pp. 13-21 ◽  
Author(s):  
Mario Rosso ◽  
Ildiko Peter ◽  
Federico Gobber
Keyword(s):  
Grain Size ◽  
Wear Resistance ◽  
Tungsten Carbide ◽  
Cobalt Content ◽  
Coarse Grained ◽  
Cemented Carbides ◽  
Grinding Wheel ◽  
Large Power ◽  
Circular Saw ◽  
Circular Saws

Circular saw blades are used exclusively for cut-off work, ranging from small manual feed operations, up to very large power fed saws commonly used for sectioning stock as it comes from a rolling mill or other manufacturing processes for long products. The teeth profile, as well as the tooth configuration are of fundamental importance for the blade performances; through a combination of blade rigidity and grinding wheel condition a good quality surface finish is attained for tools of commercial standard. The materials used for the production of circular saw blades are ranging from high speed steel to cemented carbides. In particular, cemented carbides, being characterized by high hardness and strength, are used in applications where materials with high wear resistance and toughness are required. The main constituents of cemented carbides are tungsten carbide and cobalt. Tungsten carbide imparts the alloys the necessary strength and wear resistance, whereas cobalt contributes to the toughness and ductility of the alloys. The WC-Co alloys are tailored for specific applications by the proper choice of tungsten carbide grain size and the cobalt content. The grain size of the tungsten carbide in WC-Co varies from about 40 µm to around 0.3 µm, the cobalt content from 3 to 30 wt%. The coarse grained hardmetals are mainly used in mining applications, the smallest grain size being about 3 µm and the minimum cobalt content 6 wt%. The grain size of tungsten carbide in the metal cutting industry, as well as for universal applications lies in the range of 1-2 µm. However, with the advent of near net shape manufacturing and thin walled components, the use of submicron carbide is growing, since their high compressive strength and abrasive wear resistance can be used to produce tools with a sharp cutting edge and a large positive rake angle.In this invited paper, a general overview on the actual trends in the choice of the best material when cutting special alloys will be presented and discussed. Based on the recent and past literature some examples of their up-to-date application, such as circular saws used to cut stainless steels and some high strength alloys, are talk over.

Tribological behaviour of low-pressure plasma sprayed WC-Co coatings at elevated temperatures

2019 ◽  
Vol 71 (2) ◽  
pp. 258-266
Author(s):  
Zhe Geng ◽  
Huadong Huang ◽  
Baoshan Lu ◽  
Shaohua Wu ◽  
Gaolian Shi
Keyword(s):  
Wear Resistance ◽  
Elevated Temperatures ◽  
High Hardness ◽  
Cobalt Content ◽  
Ambient Air ◽  
Low Pressure ◽  
Tribological Behaviour ◽  
Content Type ◽  
Pressure Plasma ◽  
Low Pressure Plasma

Purpose This paper aims to investigate the effect of coating microstructure, mechanical and oxidation property on the tribological behaviour of low-pressure plasma spraying (LPPS) tungsten carbide/cobalt (WC-Co) coatings. Design/methodology/approach WC-12Co and WC-17Co coatings were deposited via the LPPS spraying method. Tribological tests on the coatings were performed using a high-temperature ball-on-disc tribometer at temperatures from room temperature (RT, approximately 25 °C) up to 800 °C in ambient air. Findings WC-12Co coating contained brittle phases, pores and microcracks, which led to the low hardness, and finally promoted the splat delamination and the carbide debonding during wear. WC-17Co coating had higher cobalt content which benefited the coating to contain more WC particles, less brittle phases, pores and nearly no microcracks, and resulted in the high hardness and better wear resistance. Higher cobalt content also decelerated the oxidation rate of the coating and promoted the formation of cobalt oxides and CoWO4, which were able to maintain the load-bearing capacity and improve the tribological behaviour of the coating below 650°C. Above 650°C, the increase of oxidation degree and the decrease of mechanical property deteriorated the wear resistance of coatings. Originality/value The LPPS WC-Co coating with higher cobalt content had better tribological properties at different temperatures. The LPPS WC-Co coatings should not be used as wear-resistant coatings above 650 °C.

scholarly journals Small-Scale Mechanical Testing of Cemented Carbides from the Micro- to the Nano-Level: A Review

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 502 ◽  
Author(s):  
Naughton-Duszová ◽  
Csanádi ◽  
Sedlák ◽  
Hvizdoš ◽  
Dusza
Keyword(s):  
Mechanical Testing ◽  
Cobalt Content ◽  
Cemented Carbides ◽  
Future Research ◽  
Small Scale ◽  
Indentation Modulus ◽  
Compression Tests ◽  
Clear Trend ◽  
Testing Environment ◽  
Load Size

In this overview, we summarize the results published to date concerning the small-scale mechanical testing of WC–Co cemented carbides and similar hardmetals, describing the clear trend in the research towards ever-smaller scales (currently at the nano-level). The load-size effect during micro/nanohardness testing of hardmetals and their constituents and the influence of the WC grain orientation on their deformation, hardness, indentation modulus, fracture toughness, and fatigue characteristics are discussed. The effect of the WC grain size/orientation, cobalt content, and testing environment on damage accumulation, wear mechanisms, and wear parameters are summarized. The deformation and fracture characteristics and mechanical properties, such as the yield and compression strength, of WC–Co composites and their individual WC grains at different orientations during micropillar compression tests are described. The mechanical and fracture properties of micro-cantilevers milled from WC–Co hardmetals, single WC grains, and cantilevers containing WC/WC boundaries with differently-oriented WC grains are discussed. The physical background of the deformation and damage mechanisms in cemented carbides at the micro/nano-levels is descri and potential directions for future research in this field are outlined.

Investigation of low-pressure diamond deposition on cemented carbides

1992 ◽  
Vol 1 (5-6) ◽  
pp. 600-604 ◽  
Author(s):  
A.K. Mehlmann ◽  
S.F. Dirnfeld ◽  
Y. Avigal
Keyword(s):  
Low Pressure ◽  
Cemented Carbides ◽  
Diamond Deposition
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