Effect of Boron and Carbon Addition on the Phase Transformations during High-Energy Ball Milling and Subsequent Sintering of Si3N4+B and Si3N4+C Powder Mixtures

2016 ◽  
Vol 869 ◽  
pp. 58-63
Author(s):  
Luiz Otávio Vicentin Maruya ◽  
Bruna Rage Baldone Lara ◽  
Belmira Benedita de Lima ◽  
Vanessa Motta Chad ◽  
Gilberto Carvalho Coelho ◽  
...  

This study reports on effect of boron and carbon addition on the phase transformations during ball milling and subsequent sintering of Si3N4+B and Si3N4+C powder mixtures. Ball milling at room temperature was conducted using stainless steel vials (225 mL) and balls (19mm diameter), 300 rpm and a bal-to-powder weight ratio of 10:1. The as-milled powders were uniaxially compacted in order to obtain cylinder samples with 10 mm diameter, which were subsequently sintered under nitrogen atmosphere at 1500°C for 1h. Characterization of the as-milled powders and sintered samples was performed by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. Only peaks of Si3N4 were identified in X-ray diffractograms of as-milled Si3N4+B and Si3N4+C powders, suggesting that metastable structures were found during milling. After sintering at 1500°C for 1h, the Si3N4+BN and Si3N4+SiC ceramic composites were formed from the mechanically alloyed Si3N4+B and Si3N4+C powders.

2016 ◽  
Vol 869 ◽  
pp. 19-24
Author(s):  
Lucas Moreira Ferreira ◽  
D.S. Mégda ◽  
A.C. de Souza ◽  
Rodrigo Fernando Costa Marques ◽  
Erika Coaglia Trindade Ramos ◽  
...  

This work evaluated on the structural modification during high-energy ball milling of the Si-50C, Si-42.9C-19.1B e Si-33.3C-44.4B (at.-%) powder mixtures from elemental powders. Electron images revealed on occurrence of continuous fracture mechanisms in brittle particles during their processing, which presented rounded particles lower than 10 μm. X-ray diffraction results of Si-50C powders indicated that the intensity of Si peaks was slightly reduced after milling for 17 h, which were moved to the direction of larger diffraction angles after 7 h of milling, suggesting that carbon atoms were dissolved into the Si lattice in order to form an extended solid solution. Following, these values were increased due to the discrete exothermic formation of the SiC compound. In Si-C-B powder mixtures, the SiC and B4C compounds were formed after milling for 7 h.


2014 ◽  
Vol 802 ◽  
pp. 29-34
Author(s):  
Leandro Koji Kayano ◽  
Daniel Murusawa ◽  
Gilda Maria Cortez Pereira ◽  
Alfeu Saraiva Ramos

This work presents the results on the high-energy ball milling and hot pressing of Ni-48Ti-2Sn and Ni-45Ti-5Sn (at-%) powder mixtures. The milling process was performed in a planetary ball mill using stainless steel vial (225 mL) and hardened steel balls (19 mm diameter), rotary speed of 300 rpm, and a ball-to-powder weight ratio of 10:1. Samples were collected into the vial after different milling times: 60, 180 and 300 min. In the sequence, wet milling (isopropyl alcohol) was adopted up to 720 min in order to increase the powder yield into the vials. The as-milled and hot-pressed samples were characterized by X-ray diffraction, electron scanning microscopy, and energy dispersive spectrometry. Results indicated that the ductile particles were promptly cold-welded during the initial milling times. XRD patterns of the Ni-48Ti-2Sn powder mixture indicated that the peaks of Ni, Ti and Sn disappeared after milling for 3h. Following, peaks of NiTi and Ni4Ti3were preferentially formed during milling of Ni-Ti-Sn powders. A large amount of fine powders was yielded into the vial after wet milling for 720 min only. No significant carbon or oxygen contamination was detected by EDS analysis. Hot pressing produced homogeneous and dense samples which presented microstructures containing a large amount of the NiTi compound.


2017 ◽  
Vol 899 ◽  
pp. 3-8
Author(s):  
Luiz Otávio Vicentin Maruya ◽  
Bruno Bacci Fernandes ◽  
Mario Ueda ◽  
Alfeu Saraiva Ramos

This work reports on effect of magnesium addition on the Ti6Si2B stability in Ti-xMg-22Si-11B (x = 2 and 6 at.-%) alloys prepared by high-energy ball milling and subsequent sintering. Ball milling was conducted under Ar atmosphere in stainless steel vials and balls, 300 rpm, and a ball-to-powder weight ratio of 10:1. Following, the powders milled for 10 h were axially compacted in order to obtain cylinder samples with 6 mm diameter. To obtain the equilibrium structures the green samples were sintered at 1100°C for 4 h under Ar atmosphere. X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry were used to characterize the as-milled powders and sintered samples. Extended Ti solid solution were found in the Ti-2Mg-22Si-11B and Ti-7-Mg-Si-B powders milled for 20 min and 60 min, respectively, whereas an amorphous halo was produced on Ti-2Mg-22Si-11B powders milled for 420 min. The increase of Mg amount in the starting powder mixture has inhibited the Ti6Si2B formation in the mechanically alloyed and sintered Ti-7Mg-22Si-11B alloy.


Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 403-412
Author(s):  
Nedjima Bouzidi ◽  
Athmane Bouzidi ◽  
Raphael Oliveira Nunes ◽  
Djoudi Merabet

ABSTRACTThe present study examined the microstructure and mechanical properties of ceramic composites based on a kaolin from Djebel Debbagh, northeast Algeria, composed mainly of kaolinite and halloysite with the addition of various amounts of BaCO3. The composites were prepared by high-energy ball milling and sintered at 1100°C and 1200°C for 3 h. The samples sintered at 1200°C without BaCO3were composed mainly of mullite, which disappeared with increasing BaCO3content. X-ray diffraction investigation showed the presence of hexacelsian (BaAl2SiO6and BaAl2Si2O8), which disappeared at BaCO3contents >50 wt.% in favour of barium aluminium and barium silicate phases. At 40 wt.% BaCO3content, the porosity of the composites decreased from 0.7% to 0.1% and the microhardness increased from 7 to 8 GPa, respectively, at 1100°C and 1200°C due to the amorphous phase.


Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 728
Author(s):  
Roberto Gómez Batres ◽  
Zelma S. Guzmán Escobedo ◽  
Karime Carrera Gutiérrez ◽  
Irene Leal Berumen ◽  
Abel Hurtado Macias ◽  
...  

Air plasma spray technique (APS) is widely used in the biomedical industry for the development of HA-based biocoatings. The present study focuses on the influence of powder homogenization treatment by high-energy ball milling (HEBM) in developing a novel hydroxyapatite-barium titanate (HA/BT) composite coating deposited by APS; in order to compare the impact of the milling process, powders were homogenized by mechanical stirring homogenization (MSH) too. For the two-homogenization process, three weight percent ratios were studied; 10%, 30%, and 50% w/w of BT in the HA matrix. The phase and crystallite size were analyzed by X-ray diffraction patterns (XRD); the BT-phase distribution in the coating was analyzed by backscattered electron image (BSE) with a scanning electron microscope (SEM); the energy-dispersive X-ray spectroscopy (EDS) analysis was used to determinate the Ca/P molar ratio of the coatings, the degree of adhesion (bonding strength) of coatings was determinate by pull-out test according to ASTM C633, and finally the nanomechanical properties was determinate by nanoindentation. In the results, the HEBM powder processing shows better efficiency in phase distribution, being the 30% (w/w) of BT in HA matrix that promotes the best bonding strength performance and failure type conduct (cohesive-type), on the other hand HEBM powder treatment promotes a slightly greater crystal phase stability and crystal shrank conduct against MSH; the HEBM promotes a better behavior in the nanomechanical properties of (i) adhesive strength, (ii) cohesive/adhesive failure-type, (iii) stiffness, (iv) elastic modulus, and (v) hardness properties.


2010 ◽  
Vol 660-661 ◽  
pp. 329-334 ◽  
Author(s):  
Railson Bolsoni Falcão ◽  
Edgar Djalma Campos Carneiro Dammann ◽  
Cláudio José da Rocha ◽  
Ricardo Mendes Leal Neto

This work reports the efforts to obtain TiFe intermetallic compound by high-energy ball milling of Ti and Fe powder mixtures. This process route has been used to provide a better hydrogen intake in this compound. Milling was carried out in a SPEX mill at different times. Strong adherence of material at the vial walls was seen to be the main problem at milling times higher than 1 hour. Attempts to solve this problem were accomplished by adding different process control agents, like ethanol, stearic acid, low density polyethylene, benzene and cyclohexane at variable quantities and keeping constant other milling parameters like ball to powder ration and balls size. Better results were attained with benzene and cyclohexane, but with partial formation of TiFe compound even after a heat treatment (annealing) of the milled samples.


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