Effect of Recycled Mixed Powder on the Mechanical Properties and Microstructure of Concrete

2022 ◽  
Vol 10 (5) ◽  
pp. 1397-1414
Author(s):  
Chao Liu ◽  
Huawei Liu ◽  
Jian Wu
Keyword(s):  
Mechanical Properties ◽  
Mixed Powder

scholarly journals Enhancing the Capillary Force of Binder-Jetting Printing Ti6Al4V and Mechanical Properties under High Temperature Sintering by Mixing Fine Powder

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1354
Author(s):  
Yang Tang ◽  
Zheguan Huang ◽  
Jianming Yang ◽  
Yonglin Xie
Keyword(s):  
Mechanical Properties ◽  
Capillary Force ◽  
High Performance ◽  
Three Dimensional ◽  
Fine Powder ◽  
Green Body ◽  
Mixed Powder ◽  
Powder Bed ◽  
Polymer Binders

Binder jet 3D printing (BJ3DP) is an additive manufacturing technology that selectively deposits binder on powder to form a three-dimensional green body followed by sintering process. The low strength of green body and metallurgical issues limit the manufacture of Ti6Al4V parts with high-performance and that are lightweight. In this study, thermal-bubble inkjet technology was used to print Ti6Al4V parts via jetting low-concentration in-situ polymer binders. In addition, a method for mixing fine powder was used to enhance the capillary force of the powder bed and mechanical properties of the parts. The results show that the capillary force was enhanced from 8.35 kPa for pure powder to 16.27 kPa for mixed powder by mixing fine powder. The compression strength of green body was enhanced from 1.5 MPa to 3.21 MPa. After sintering, the sample with mixed powder sintered at 1420 °C for 2 h had achieved a maximum density of 95.2%, microhardness of 316 HV, and yield stress of 589 MPa. The relative density of 95.2% of Ti6Al4V parts fabricated by BJ3DP technology in our study is significantly higher than the value reported in the existing literature. Finally, the porous structure with a size of 550 μm was fabricated. Results presented demonstrate that BJ3DP can produce Ti6Al4V parts with excellent properties.

Effect of Al-5Zr-1.1B Grain Refiner on Microstructure and Mechanical Properties of AZ91D Magnesium Alloy

2015 ◽  
Vol 816 ◽  
pp. 337-342
Author(s):  
Shun Cheng Wang ◽  
Zheng Hua Huang ◽  
Wen Jun Qi ◽  
Kai Hong Zheng
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
Average Diameter ◽  
Grain Refiner ◽  
Mixed Powder ◽  
Az91d Magnesium Alloy ◽  
Microstructure And Mechanical Properties ◽  
Equiaxed Grains ◽  
Addition Amount

An Al-5Zr-1.1B grain refiner was prepared by in-situ synthesis from Al melt and K2ZrF4+KBF4 mixed powder. The microstructure of Al-5Zr-1.1B grain refiner was analyzed by XRD, SEM and EDS. The effect of Al-5Zr-1.1B grain refiner on the microstructure and mechanical properties of AZ91D magnesium alloy were studied. Results show that a large number of fine ZrB2 particles were observed in the Al-5Zr-1.1B grain refiner and the ZrB2 particles could act as the heterogeneous nuclei of α-Mg grains. With the increase of the addition amount of Al-5Zr-1.1B grain refiner, the α-Mg grains of AZ91D magnesium alloy were refined from coarse dendrites to equiaxed grains. When the addition amount of Al-5Zr-1.1B grain refiner increased to 0.6%, the α-Mg grains of AZ91D magnesium alloy were refined to fine equiaxed grains with an average diameter of 45 μm, and the tensile strength and elongation of AZ91D magnesium alloy were improved to 195.3 MPa and 3.94%, respectively. The α-Mg grains average diameter of AZ91D magnesium alloy decreased by 73.5% and the tensile strength and elongation improved by 25.9% and 27.9% compared with that of AZ91D magnesium alloy without adding the Al-5Zr-1.1B grain refiner. It is concluded that the Al-5Zr-1.1B is an effective grain refiner to refine the α-Mg grains of AZ91D magnesium alloy.

Microstructure and Mechanical Properties of ZrO2(Y2O3)-Al2O3 Nano Composites Prepared by Spark Plasma Sintering

2008 ◽  
Author(s):  
Shufeng Li ◽  
Hiroshi Izui ◽  
Michiharu Okano ◽  
Weihua Zhang ◽  
Taku Watanabe
Keyword(s):  
Mechanical Properties ◽  
Spark Plasma Sintering ◽  
Sintering Temperature ◽  
Alumina Ceramic ◽  
The Other ◽  
Sintering Behavior ◽  
Nanocomposite Powder ◽  
Mixed Powder ◽  
Plasma Sintering ◽  
Spark Plasma

Zirconia (Y2O3)-alumina ceramic nanocomposites were fabricated by spark plasma sintering (SPS). A commercially available nanocomposite powder TZP-3Y20A was used as starting powder, the other from conventionally mechanical mixed powder 3YSZ-20A used for comparison. The effect of sintering temperature on the densification, sintering behavior, mechanical properties, and microstructure of the composites were investigated. The results show that the density increase with increasing of sintering temperature, and thus mechanical properties were strengthened with enhancing of densification. The nanocomposite powder TZP-3Y20A was easily sintered and good mechanical properties were achieved, compared with the powder from conventionally mechanical mixed, where the maximum strength and toughness of composites are 967 MPa and 5.27 MPam1/2, respectively.

scholarly journals Fabrication of TiN Particle-Dispersed Al2O3 Composites Utilizing High N2-Pressure SHS

2011 ◽  
Vol 13 (3-4) ◽  
pp. 115
Author(s):  
Ken Hirota ◽  
Hajime Yagura ◽  
Katsuya Takaoka ◽  
Masaki Kato
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Thermal Decomposition ◽  
High Pressure ◽  
Bending Strength ◽  
Hot Isostatic Pressing ◽  
Mixed Powder ◽  
Second Stage ◽  
Powder Compacts ◽  
Tin Content

<p>Fabrication of fine TiN particle-dispersed dense Al<sub>2</sub>O<sub>3</sub> composites with the compositions of Al<sub>2</sub>O<sub>3</sub>/TiN=100/0~90/10 vol% has been conducted from Al<sub>2</sub>O<sub>3</sub>/(Ti,TiN<sub>0.3</sub>) mixed powder compacts by capsule-free hot isostatic pressing (HIP) utilizing high-pressure N<sub>2</sub> SHS. Fine Ti powders (φ ~ 0.3 μm) with TiN<sub>0.3 </sub>phase were prepared by thermal decomposition of planetary ball-milled fine TiH<sub>2</sub> powders at 400°C (673 K) for 1 h in a vacuum, followed by heating in N<sub>2</sub> at 200 °C (473 K) for 2 h. The Al<sub>2</sub>O<sub>3</sub> powder compacts (relative densities of 57.2-57.8%) with homogeneously dispersed (Ti,TiN<sub>0.3</sub>) particles were prepared. The mixed powder compacts were hot isostatically pressed (HIPed) under the conditions of 1350°C (1623 K) at 7 MPa N<sub>2 </sub>for 1 h, followed by the heating at the same temperature for 2 h under 196 MPa-N<sub>2</sub>. At the first stage of heating [1350°C (1623K)/7MPa/1h], solid/gas reaction of SHS between (Ti,TiN<sub>0.3</sub>) and N<sub>2</sub> was introduced to form TiN and densification of the Al<sub>2</sub>O<sub>3</sub> powder compacts up to the relative density of 92-93% with closed pores was performed. And at the sequent second stage [1350 °C (1623K)/196MPa/2h], densification of the most of pre-sintered composites consisting of Al<sub>2</sub>O<sub>3</sub> and TiN reached higher relative densities than 98.5%. Dispersion of TiN particles (~φ 0.30 μm) in the composites suppressed the grain growth of Al<sub>2</sub>O<sub>3</sub> during HIP-sintering. Mechanical properties, such as bending strength (σ<sub>b</sub>), Vickers hardness (<em>H</em><sub>V</sub>), fracture toughness (<em>K</em><sub>1C</sub>), and electrical resistivity (ρ) of the composites were evaluated as a function of TiN content; the maximum values of σ<sub>b</sub>=640 MPa, <em>H</em><sub>V</sub>=19.5 GPa, and <em>K</em><sub>IC</sub>=4.5 MPa・m<sup>1/2 </sup>were obtained in the Al<sub>2</sub>O<sub>3</sub>/TiN=97/3~95/5 vol% composites. Among the composites, the lowest ρ value of 2.6×10<sup>3</sup> Ω・m was attained at Al<sub>2</sub>O<sub>3</sub>/TiN=90/10 vol% composite.</p>

scholarly journals Influence of Heat Treatments on Microstructure and Mechanical Properties of Ti–26Nb Alloy Elaborated In Situ by Laser Additive Manufacturing with Ti and Nb Mixed Powder

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 61 ◽  
Author(s):  
Jing Wei ◽  
Hongji Sun ◽  
Dechuang Zhang ◽  
Lunjun Gong ◽  
Jianguo Lin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Annealing Temperature ◽  
Annealing Treatment ◽  
High Strength ◽  
Fiber Texture ◽  
Laser Additive Manufacturing ◽  
Mixed Powder ◽  
Microstructure And Mechanical Properties

In the present work, a Ti–26Nb alloy was elaborated in situ by laser additive manufacturing (LAM) with Ti and Nb mixed powders. The alloys were annealed at temperatures ranging from 650 °C to 925 °C, and the effects of the annealing temperature on the microstructure and mechanical properties were investigated. It has been found that the microstructure of the as-deposited alloy obtained in the present conditions is characterized by columnar prior β grains with a relatively strong <001> fiber texture in the build direction. The as-deposited alloy exhibits extremely high strength, and its ultimate tensile strength and yield strength are about 799 MPa and 768 MPa, respectively. The annealing temperature has significant effects on the microstructure and mechanical properties of the alloys. Annealing treatment can promote the dissolution of unmelted Nb particles and eliminate the micro-segregation of Nb at the elliptical-shaped grain boundaries, while increasing the grain size of the alloy. With an increase in annealing temperature, the strength of the alloy decreases but the ductility increases. The alloy annealed at 850 °C exhibits a balance of strength and ductility.

Effect of VC and C Addition on Mechanical Properties and Microstructures of WC-Co Hardmetals Processed in Nitrogen-Based Atmosphere

2012 ◽  
Vol 59 (2) ◽  
Author(s):  
R. J. Talib ◽  
A. A. Mahaidin ◽  
S. A. Manaf ◽  
M. A. Selamat
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Powder Metallurgy ◽  
Test Results ◽  
Powder Metallurgy Technique ◽  
Dense Structure ◽  
Mixed Powder ◽  
Vicker’S Microhardness ◽  
Scanning Electron ◽  
Microhardness Tester

The WC-Co, WC-Co-VC and WC-Co-C samples are fabricated using powder metallurgy technique. The mixed powder is compacted under the pressure of 625 MPa, cold-isostatic pressed at 200 MPa and sintered at temperature in the range of 1350 – 1450°C nitrogen-based atmosphere. The mechanical properties of the samples are analyzed using Vicker’s microhardness tester, universal tensile machine and scanning electron microscope. Test results reveal that WC-Co-C sample has better mechanical properties as compared to WC-Co and WC-Co-VC due to the formation of homogeneous and dense structure.

The microstructure and mechanical properties of Co/YCF102 composite coating

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wenchao Xi ◽  
Boxue Song ◽  
Jinlong Dong ◽  
Tianqi Zhang ◽  
Tianbiao Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Composite Coating ◽  
Laser Cladding ◽  
Machine Tools ◽  
Base Material ◽  
Mixed Powder ◽  
Content Type ◽  
High Microhardness ◽  
Aisi 1045

Purpose Laser cladding has been used in the field of repairing damaged parts of machine tools due to its advantages of less processing restrictions and easy formation of a good metallurgical bond with the base material. However, the mechanical properties of the coating sometimes cannot meet the process requirements. Therefore, the purpose of this paper is to prepare coatings with high microhardness and flexural strength. Design/methodology/approach The YCF102 alloy powder was mixed with different contents of Co and tested for laser cladding on AISI 1045 substrate under the same process parameters. The main phase composition of the coating was revealed by the XRD results. The main chemical composition of the coating was determined by the SEM and EDS results. In addition, the effect of Co content on the microstructure, microhardness and flexural strength of the coatings was investigated. Findings The results show that when the Co content is 2 wt% and 4 wt%, Co does not form compounds with other elements, but is uniformly distributed in the coating. And when the Co content is 6 wt% and 8 wt%, the Co reacts with Fe in the coating and generates Co3Fe7 in situ. The increase in Co did not result in a monotonic change in microhardness, but significantly improved the flexural strength and the flatness of the microstructure of the coating. When the Co content of the mixed powder is 8 wt%, the coating has high microhardness and flexural strength. Originality/value Co/YCF102 composite coating with high microhardness and flexural strength was prepared. This paper provides a theoretical and practical basis for research in the area of repairing damaged parts of machine tools by laser cladding.

A Method for the Production of Large Sized Al-B4C-Al2O3np Nanocomposites through Liquid-State Process

2017 ◽  
Vol 753 ◽  
pp. 84-92
Author(s):  
Wei Liu ◽  
Qiu Lin Li ◽  
Wei Liu ◽  
Guo Gang Shu ◽  
Qi Sun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Ball Milling ◽  
Liquid State ◽  
Room Temperature ◽  
Milling Time ◽  
Mixed Powder ◽  
State Process ◽  
Semi Solid

The paper introduces a new method to produce large sized Al-B4C-Al2O3np composites, which combines ball milling to prepare Al2O3np/Al mixed powder and semi-solid casting to contribute the injection of Al2O3np/Al mixed powder into the melt. The deformation performance of Al2O3np and micro-Al through ball milling with different Al/Al2O3np ratios, different milling time and different balls were studied respectively. It was revealed that micro-Al particles were milled from twisted and crimpled foil pieces to shuttles with Al2O3np embedded on it through 4h milling with 10mm balls. And we consider it as the best bonding between Al2O3np and micro-Al we could attain. And a plate of 25kg of Al-B4C-Al2O3np composite was fabricated successfully with the injection of the Al2O3np/Al mixed powder. Spherical Al2O3np of 300nm and needle-like TiB2 with 200nm in radius and 800nm-4μm in length were found in SEM photographs. Tensile properties of Al-B4C-Al2O3np composites were tested at room temperature and high temperature. It was showed higher mechanical properties than Al-B4C composites at room temperature and elevated temperature. Particularly, a 40% increase of UTS of Al-15wt.% B4C-1wt.%Al2O3np at 350°C was observed.

scholarly journals Strengthening of Nanocrystalline Al with Al3Zr Core-Shell Structure

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1144
Author(s):  
Dora Janovszky
Keyword(s):  
Mechanical Properties ◽  
Shell Structure ◽  
Hot Pressing ◽  
Room Temperature ◽  
High Energy ◽  
Core Shell ◽  
Mixed Powder ◽  
Reinforcing Particles ◽  
Core Shell Structure ◽  
Nanocrystalline Phases

High-density Al-based composites reinforced with ten-wt.% recycled nanocrystalline CuZrAgAl particles have been fabricated by mechanical milling, cold- and hot-pressing. The microstructures, phase transformations, and mechanical properties of the mixed powder and sintered samples were investigated. After milling in a ball mill for 30 h, the microhardness of the mixed powder increases to 301 ± 31 HV0.01 and 222 ± 10 HV0.01 without and with ethanol milling, respectively. On account of the interdiffusion, the melting temperature of mixed powder reduces to 574 ± 5.0 °C and 627.5 ± 6.5 °C after 30 h milling. The study showed that the reinforcing particles are homogeneously distributed in the sintered nanocrystalline Al-based composites. During the hot-pressing, a shell zone forms at the interface of reinforcing particles during hot pressing after high energy milling with a minimum of ten hours milling time. This shell zone consists of Al3Zr (D023) phase. The coarsening resistant core-shell structure and grain refinement greatly improve mechanical properties. The compression strength at room temperature varies between 650 and 800 MPa at room temperature and is 380 MPa at 400 °C for the composite containing ten-wt.% of the Cu-Zr-based amorphous-nanocrystalline phases. The Brinell hardness of the sintered composite is 329 HB.

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