Gonzalez-Ojeda, Roberto
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Preferred name
Gonzalez-Ojeda, Roberto
Official Name
Gonzalez Ojeda, Roberto
Alternative Name
robglez
González-Ojeda, R.
Main Affiliation
ORCID
Scopus Author ID
56314856300
Researcher ID
DTL-2716-2022

Research Output
Now showing 1 - 4 of 4
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HIP after sintering of ultrafine WC–Co hardmetals

2005 , Sánchez, J. M. , Ordóñez, Alejandro , Gonzalez-Ojeda, Roberto

This paper analyses the changes induced by HIP after sintering on the microstructure and mechanical properties of WC–7wt.%Co ultrafine hardmetal grade. The well known correlation between porosity reduction and fracture strength improvement is confirmed in these compositions, this being more effective at HIP temperatures above the eutectic point of the alloy. In absence of GGI, hardness decreases continuously as the HIP temperature increases. However, for specimens containing VC and Cr3C2 additions, hardness increases as the HIP temperature increases from 1200 °C to 1400 °C. This anomalous trend, confirmed by WC grain size observations, could be related to the activation of coalescence mechanisms during solid state HIPing, which are inhibited by the presence of a liquid phase.

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Sintering + HIP of Ultrafine WC-Co Hardmetals

2007 , Ordóñez, Alejandro , Gonzalez-Ojeda, Roberto , Sánchez, J.M.

Abstract not available.

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Using FEM to determine temperature distribution in a blast furnace crucible

2000 , Verdeja, Luis Felipe , Gonzalez-Ojeda, Roberto , Ordóñez, Alejandro

Temperature distribution in the crucible of a blast furnace is an important operation variable that is a function of the materials used in its construction, temperatures reached in the pig iron-refractory interface, and cooling-system performance. Defining the crucible zones where high shear and tensile stresses are reached is an important step in developing a tribological model to understand and predict high wear zones and crucible life. In this work, temperature distribution was simulated using the finite-element method for a blast furnace built following the ceramic solution (oxide and nitride ceramics in contact with the pig iron and carbon and microporous graphite blocks in contact with the refrigeration system).

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Wear in ultrafine hardmetal mills manufactured by sinter + HIP

2006-12-01 , Ordóñez, Alejandro , Gonzalez-Ojeda, Roberto , Sánchez-Moreno, José Manuel

Ultrafine WC-Co milling tools were wear-tested in finishing machining conditions. Mills manufactured in the laboratory followed the powder metallurgy route for ultrafine grades. Total density in hardmetal grades of 0.2 and 0.4 μm was achieved through the Sinter + HIP technique. Wear in laboratory mills was compared with wear in coarse and ultrafine grade commercial mills. All mills cutting edges suffered wear mainly in the abrasive and chipping form. Chipping was excessive and peculiar in form in the laboratory mills; a slight presence of the fragile η phase was discovered. Laboratory mills showed similar wear to the commercial coarse grades, and much more than that of commercial ultrafine grades. A lack of toughness is suggested due to a small difference in the WC mean grain size, in the Co mean free path (λ) and in its distribution: homogeneous in laboratory mills and heterogeneous in the commercial ones. ©Metal Powder Industries Federation (MPIF)

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