Luno-Bilbao, C. (Carmen)
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- About the relationship of the processing conditions, mechanical properties, and microstructure of a co-precipitated Fe/Cu prealloyed powder.(Elsevier, 2023-03) Veiga, A. (Angela); Peña-Ezpeleta, G. (Guillén); Iturriza-Zubillaga, I. (Iñigo); Ausejo-Muñoz, S. (Sergio); Vielma, N. (Nirco); Luno-Bilbao, C. (Carmen)The sinterability of a commercial Fe-Cu pre-alloyed powder, designed to be used as a metallic bond in diamond impregnated tools, has been greatly analyzed by combining dilatometry, computational thermodynamic calculations, and microstructural analysis. The effect of sintering temperature and alloying elements such as graphite and iron phosphide have been taken into consideration in order to demonstrate the capability of tailoring final properties through different strategies, and dilatometry and microstructural analysis have been used to understand the densification process of the alloys. Solid phase sintering was the mechanism taking place during thermal cycle. In fact, a liquid phase appears but because of the high densification level at that time mechanisms associated with LPS do not contribute to densification. Discussion about me-chanical properties has been related to key microstructural phenomena, i.e., grain growth, phase transformation, precipitation, and solid solution. Obtained hardness ranged from 83 HRB to 106 HRB with yield stresses between 450 MPa and 700 MPa and elongations above 3%, while final tensile properties similar to those obtained by cobalt-based powders processed by hot pressing were also obtained.
- Synthesis and electrochemical properties of Ti-Si alloys prepared by mechanical alloying and heat treatment(MDPI AG, 2018) García, C. (Carolina); Guzmán, D. (Danny); Aguilar, C. (Claudio); Sepúlveda, R. (Rossana); Iturriza-Zubillaga, I. (Iñigo); Rojas, P. (Paula); Soliz, Á. (Álvaro); Luno-Bilbao, C. (Carmen)The aim of this work was to study the synthesis and electrochemical properties of Ti 2 wt %-Si alloys prepared by mechanical alloying (MA) and heat treatment. The MA process was performed under Ar atmosphere. The structural, morphological, and compositional evolutions during the milling and subsequent heat treatment were investigated by X-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy. The electrochemical behavior was evaluated by open circuit potential and linear sweep voltammetry measurements. The results showed that the MA process promotes the formation of a supersaturated α-Ti-Si solid solution. During heat treatment, the Si remaining in the mechanically alloyed powders and the Si from the α-Ti-Si supersaturated solid solution reacted with Ti to form Ti-Si intermetallic compounds. These compounds have a fine and homogeneous distribution in the α-Ti matrix, which cannot be achieved by conventional casting methods. Additionally, the electrochemical evaluations revealed that the mechanically alloyed and heat-treated Ti 2 wt %-Si powders have better corrosion resistance in 1.63 M H2SO4 than the pure Ti and MA Ti-Si samples. This is likely due to the particular microstructure produced during the milling and subsequent heat treatment.
- New strategies based on liquid phase sintering for manufacturing of diamond impregnated bits(Elsevier, 2024) Iturriza-Zubillaga, I. (Iñigo); Veiga, A. (A.); Polvorosa, N.G. (N.G.); Luno-Bilbao, C. (Carmen)Infiltration is an extensively used technique in the production of Diamond Impregnated Bits (DIBs) commonly used for drilling in both mineral exploration and the Oil&Gas industry. This paper describes research into liquid phase sintering (LPS) as an alternative to commonly used infiltration processes. The great wear resistance and high cutting ability necessary for these tools in turn requires a high diamond concentration and a large volume fraction of wear-resistant components, such as tungsten carbide and/or eutectic tungsten carbide particles. With relatively large particles that do not contribute to densification, the LPS system researched was designed with a relatively large amount of permanent liquid phase sintering, with, rearrangement being selected as the primary densification mechanism owing to the stability of the hard phases. After testing various binder phases and evaluating the influence of the liquid phase volume fraction and presence of some sintering aids, results are promising. Bonds with better sintering behaviour were characterized, while hardness, microstructure, abrasive wear resistance, and interaction with diamonds were studied. The proposed 35NiP25Cu40WC bond processed by LPS attained hardness of 66 HRA and wear coefficient of 20 mm3/MPa, levels similar to those obtained by hot pressed components currently used in the diamond drilling tool industry (19 mm3/MPa).