The structure and phase composition of the cermet charge in the Al‒Al2O3 system obtained using mechanical processing of aluminum powder in a planetary ball mill

2021 ◽  
pp. 31-38
Author(s):  
D. A. Ivanov ◽  
G. E. Val'yano ◽  
T. I. Borodina
Keyword(s):  
Aluminum Powder ◽  
Amorphous Carbon ◽  
Ball Mill ◽  
Bending Strength ◽  
Exothermic Reaction ◽  
Planetary Ball Mill ◽  
Mechanical Processing ◽  
Aluminum Particles ◽  
Industrial Grade ◽  
The Impact

The cermet charge in the Al‒Al2O3 system was obtained by mechanical processing (MP) in a planetary ball mill of aluminum powder of the industrial grade PAP-2 (GOST 5494‒95), consisting of flake particles of submicron thickness with a coating of stearin. Depending on the MP modes used, 4 types of charge were obtained, the bulk density of which varied from 0,33 to 1,1 g/cm3. For all types of charge, the synthesis of the α-Al2O3 phase was observed as a result of the exothermic reaction of the interaction of air oxygen with the surface of aluminum particles during the MP. It is also possible to form boehmite and gibbsite when the activated surface of Al particles interacts with atmospheric water vapor. The local X-ray spectral analysis (EDX) was used to detect X-ray amorphous carbon in the composition of the charge, the appearance of which is associated with the impact- shearing effect of grinding bodies, leading to the nucleation of X-ray amorphous carbon inclusions due to the termal destruction of stearin. The maximum bending strength of the sintered cermet was 550 MPa. This cermet is characterized by a discrete fracture: the formation of dimples as a result of the shear of layered packets under the action of tangential stresses. The revealed mechanisms cermet’s fractures allow us to establish the optimal modes of MP of powder compositions for obtaining various constructional elements from them.

scholarly journals Particle Impact Energy Variation with the Size and Number of Particles in a Planetary Ball Mill

2021 ◽  
Vol 333 ◽  
pp. 02016
Author(s):  
Fumie Hirosawa ◽  
Tomohiro Iwasaki ◽  
Masashi Iwata
Keyword(s):  
Particle Size ◽  
Impact Energy ◽  
Ball Mill ◽  
Mechanical Energy ◽  
Planetary Ball Mill ◽  
Particle Impact ◽  
Particle Collisions ◽  
Grinding Balls ◽  
The Impact ◽  
Number Of Particles

To investigate the mechanical energy applying to the particles in a grinding process using a planetary ball mill, the impact energy of particles was estimated by simulating the behavior of the particles and grinding balls using the discrete element method (DEM) under different conditions of the size and number of particles, corresponding to their variations during milling. As the impact energy contributing to the particle breakage, we focused on the particle impact energy generated at particle-to-grinding ball/wall and particle-to-particle collisions. The particle size and the number of particles affected the level of particle impact energy at a single collision and the number of collisions of particles, respectively, resulting in an increase of the total impact energy of particles with decreasing particle size and increasing number of particles. The result suggests that milling conditions such as the size of grinding balls should be adjusted appropriately based on the variation of the size and number of particles so that the particles can receive large amounts of the impact energy during milling.

Fast, solvent-free and highly enantioselective fluorination of β-keto esters catalyzed by chiral copper complexes in a ball mill

2017 ◽  
Vol 19 (7) ◽  
pp. 1674-1677 ◽  
Author(s):  
Yifeng Wang ◽  
Haojiang Wang ◽  
Yidong Jiang ◽  
Cheng Zhang ◽  
Juanjuan Shao ◽  
...  
Keyword(s):  
Ball Mill ◽  
Copper Complexes ◽  
Solvent Free ◽  
Planetary Ball Mill ◽  
Keto Esters ◽  
Solvent Free Conditions

A fast and highly enantioselective fluorination of β-keto esters catalyzed by diphenylamine linked bis(oxazoline)-Cu(OTf)2 complexes under solvent-free conditions has been developed using a planetary ball mill.

scholarly journals Implementing a digital health model of care in Australian youth mental health services: protocol for impact evaluation

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sarah Piper ◽  
Tracey A. Davenport ◽  
Haley LaMonica ◽  
Antonia Ottavio ◽  
Frank Iorfino ◽  
...  
Keyword(s):  
Mental Health ◽  
Mental Health Services ◽  
Health Services ◽  
Impact Evaluation ◽  
Digital Health ◽  
Youth Mental Health ◽  
Model Of Care ◽  
Health Service Provision ◽  
Industrial Grade ◽  
The Impact

Abstract Background The World Economic Forum has recently highlighted substantial problems in mental health service provision and called for the rapid deployment of smarter, digitally-enhanced health services as a means to facilitate effective care coordination and address issues of demand. In mental health, the biggest enabler of digital solutions is the implementation of an effective model of care that is facilitated by integrated health information technologies (HITs); the latter ensuring the solution is easily accessible, scalable and sustainable. The University of Sydney’s Brain and Mind Centre (BMC) has developed an innovative digital health solution – delivered through the Youth Mental Health and Technology Program – which incorporates two components: 1) a highly personalised and measurement-based (data-driven) model of youth mental health care; and 2) an industrial grade HIT registered on the Australian Register of Therapeutic Goods. This paper describes a research protocol to evaluate the impact of implementing the BMC’s digital health solution into youth mental health services (i.e. headspace - a highly accessible, youth-friendly integrated service that responds to the mental health, physical health, alcohol or other substance use, and vocational concerns of young people aged 12 to 25 years) within urban and regional areas of Australia. Methods The digital health solution will be implemented into participating headspace centres using a naturalistic research design. Quantitative and qualitative data will be collected from headspace health professionals, service managers and administrators, as well as from lead agency and local Primary Health Network (PHN) staff, via service audits, Implementation Officer logs, online surveys, and semi-structured interviews, at baseline and then three-monthly intervals over the course of 12 months. Discussion At the time of publication, six headspace centres had been recruited to this study and had commenced implementation and impact evaluation. The first results are expected to be submitted for publication in 2021. This study will focus on the impact of implementing a digital health solution at both a service and staff level, and will evaluate digital readiness of service and staff adoption; quality, usability and acceptability of the solution by staff; staff self-reported clinical competency; overall impact on headspace centres as well as their lead agencies and local PHNs; and social return on investment.

Effect of Spark Plasma Sintering on the Microstructure Evolution and Properties of M3:2 High-Speed Steel

2014 ◽  
Vol 788 ◽  
pp. 329-333
Author(s):  
Rui Zhou ◽  
Xiao Gang Diao ◽  
Jun Chen ◽  
Xiao Nan Du ◽  
Guo Ding Yuan ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Spark Plasma Sintering ◽  
High Speed ◽  
Bending Strength ◽  
Sintering Temperature ◽  
High Speed Steel ◽  
Continuous Heating ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Impact

Effects of sintering temperatures on the microstructure and mechanical performance of SPS M3:2 high speed steel prepared by spark plasma sintering was studied. High speed steel sintering curve of continuous heating from ambient temperature to 1200°C was estimated to analyze the sintering processes and sintering temperature range. The sintering temperature within this range was divided into groups to investigate hardness, relative density and microstructure of M3:2 high-speed steel. Strip and quadrate carbides were observed inside the equiaxed grains. SPS sintering temperature at 900°C can lead to nearly full densification with grain size smaller than 20μm. The hardness and bending strength are higher than that of the conventionally powder metallurgy fabricated ones sintered at 1270°C. However, fracture toughness of the high speed steel is lower than that of the conventional powder metallurgy steels. This can be attributed to the shape and distribution of M6C carbides which reduce the impact toughness of high speed steels.

Bending Strength and Fracture Behaviour of Metal-Ceramic Interpenetrating Phase Composites Manufactured by Using Semi-Solid Forming Technology

2022 ◽  
Vol 327 ◽  
pp. 111-116
Author(s):  
Laura Schomer ◽  
Kim Rouven Riedmüller ◽  
Mathias Liewald
Keyword(s):  
Bending Strength ◽  
Fracture Behaviour ◽  
Structural Characteristics ◽  
Process Window ◽  
Metallic Material ◽  
Forming Technology ◽  
Metal Ceramic ◽  
Semi Solid ◽  
The Impact ◽  
Interpenetrating Phase Composites

Interpenetrating Phase Composites (IPC) belong to a special category of composite materials, offering great potential in terms of material properties due to the continuous volume structure of both composite components. While manufacturing of metal-ceramic IPC via existing casting and infiltration processes leads to structural deficits, semi-solid forming represents a promising technology for producing IPC components without such defects. Thereby, a solid open pore body made of ceramic is infiltrated with a metallic material in the semi-solid state. Good structural characteristics of the microstructure as the integrity of the open-pore bodies after infiltration and an almost none residual porosity within the composites have already been proven for this manufacturing route within a certain process window. On this basis, the following paper focuses on the mechanical properties such as bending strength of metal-ceramic IPC produced by using semi-solid forming technology. Thereby, the impact of the significant process parameters on these properties is analysed within a suitable process window. Furthermore, a fractographic analysis is carried out by observing and interpreting the fracture behaviour during these tests and the fracture surface thereafter.

scholarly journals The Role of Thin-Film Vacuum-Plasma Coatings and Their Influence on the Efficiency of Ceramic Cutting Inserts

Coatings ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 287 ◽  
Author(s):  
Marina Volosova ◽  
Sergey Grigoriev ◽  
Alexander Metel ◽  
Alexander Shein
Keyword(s):  
Bending Strength ◽  
Surface Defects ◽  
Cutting Tools ◽  
High Energy ◽  
Radius Of Curvature ◽  
Sic Ceramic ◽  
Operational Tests ◽  
Mechanical Fastening ◽  
Cutting Inserts ◽  
The Impact

The main problem with ceramics used in cutting tools is related to the unpredictable failures caused by the brittle fracturing of ceramic inserts, which is critical for the intermittent milling of cyclic loading. A 125-mm-diameter eight-toothed end mill, with a mechanical fastening of ceramic inserts, was used as a cutting tool for milling hardened steel (102Cr6). For the experiments, square inserts of the Al2O3 + SiC ceramic were used and compared with the samples made of Al2O3 + TiC to confirm the obtained results. The samples were coated with diamond-like coating (DLC), TiZrN, and TiCrAlN coatings, and their bending strength and adhesion were investigated. Investigations into the friction coefficient of the samples and operational tests were also carried out. The effect of smoothing the microroughness and surface defects in comparison with uncoated inserts, which are characteristic of the abrasive processing of ceramics, was investigated and analyzed. The process developed by the authors of the coating process allows for the cleaning and activation of the surface of ceramic inserts using high-energy gas atoms. The impact of these particles on the cutting edge of the insert ensures its sharpening and reduces the radius of curvature of its cutting edges.

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