scholarly journals Preparation of Bulk TiZrNbMoV and NbTiAlTaV High-Entropy Alloys by Powder Sintering

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1748
Author(s):  
Yaqi Wu ◽  
Peter K. Liaw ◽  
Yong Zhang
Keyword(s):  
Raw Materials ◽  
Testing Machine ◽  
Compression Rate ◽  
High Entropy Alloys ◽  
Alloy Structure ◽  
Metal Compounds ◽  
High Entropy ◽  
Universal Testing ◽  
Powder Sintering ◽  
Scanning Electron

The refractory HEAs block material was prepared by powder sintering, using an equal atomic proportion of mixed TiZrNbMoV and NbTiAlTaV metal powder raw materials. The phase was analyzed, using an XRD. The microstructure of the specimen was observed, employing a scanning electron microscope, and the compressive strength of the specimen was measured, using an electronic universal testing machine. The results showed that the bulk cubic alloy structure was obtained by sintering at 1300 °C and 30 MPa for 4 h, and a small amount of complex metal compounds were contained. According to the pore distribution, the formed microstructure can be divided into dense and porous zones. At a compression rate of 10−4s−1, the yield strengths of TiZrNbMoV and NbTiAlTaV alloys are 1201 and 700 MPa, respectively.

scholarly journals PENGEMBANGAN PAPAN PEREDAM BUNYI MELALUI MODIFIKASI NANO SILIKAT AMPAS TEBU PG KREMBOENG DENGAN TEMPLATE SERAT SABUT KELAPA

2019 ◽  
Author(s):  
Hengky Herdianto ◽  
Mochamad Alfi Zahwanul Farich
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Modulus Of Elasticity ◽  
Internal Bond ◽  
Testing Machine ◽  
Sound Level ◽  
Sound Level Meter ◽  
Universal Testing ◽  
Level Meter ◽  
Scanning Electron

Manusia memiliki batas kemampuan mendengar suara pada rentang hingga 140 dB, lebih daripada itu akan terjadi kerusakan pada organ-organ dalam gendang telinga. Ampas tebu PG Kremboeng mengandung 70,97% silikat murni yang berpotensi memberikan penguatan pada papan serat dan meningkatkan performa serap bunyi. Metode yang digunakan untuk sintesis nano silikat ampas tebu dilakukan dengan cara Pretreatment BBA, tukar kation silikat, dan pencucian gel kering. Komponen silikat dan produk lain dalam ampas tebu ditentukan menggunakan difraksi sinar-X (XRD). Morfologi xerogels nano silikat dan papan serat telah diteliti dengan menggunakan Scanning Electron Microscopy (SEM). Daya serap ditentukan dari berat sebelum dan sesudah perendaman dalam air 24 jam. Pengujian keteguhan patah dan Modulus of Elasticity dilakukan dengan Universal Testing Machine. Uji Internal Bond direkatkan pada dua buah blok alumunium dengan perekat besi dan dibiarkan mengering. Koefisien serap diukur dengan sound level meter. Berdasarkan pola XRD, dapat diketahui bahwa terdeteksi medium silicate hydroxide. Berdasarkan mikrograf SEM dapat diketahui suatu struktur bongkahan yang memanjang halus terdiri atas kumpulan-kumpulan partikel nano silikat pada papan dengan template serat sabut kelapa. Sampel terbaik dalam penelitian ini adalah I (60%;17%;23%) dengan nilai DSA 82,38%, MOR 102,84 kg/cm2, MOE 11.228,52 kg/cm2, dan IB 0,83 kg/cm2. Interval nilai koofisien serap taraf intensitas bunyi antar sampel adalah 0,527 < x < 1,000 pada pagi hari, 0,544 < x < 1,000 pada siang hari, dan 0,538 < x < 1,000 pada malam hari. Sehingga secara keseluruhan interval pada segala kondisi waktu adalah 0,527 < x < 1,000.

Pressure Influence on the AlCrFeNiMn/Graphite High Entropy Composite Microhardness

2017 ◽  
Vol 750 ◽  
pp. 9-14
Author(s):  
Gabriela Popescu ◽  
Mihai Branzei ◽  
Cristian Aurelian Popescu ◽  
Alecs Andrei Matei ◽  
Roxana Trusca ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
High Entropy Alloys ◽  
X Rays ◽  
High Entropy ◽  
Graphite Particles ◽  
The Matrix ◽  
Microhardness And Microstructure ◽  
Near Net Shape ◽  
Chemical Distribution ◽  
Scanning Electron

During the last years, mechanical alloying technique for high entropy alloys (HEAs) has been more often approached due to the good homogenous chemical distribution and near net shape technology provided by the respectively process. A new composite material having the matrix as HEA reinforced with graphite particles was designed. The graphite particles addition in the high entropy matrix (AlCrFeNiMn) improves the particles weldability during mechanical alloying and assures a good creep behavior for the final product. The aim of this paper is to investigate the pressure influence on the microhardness as dependence of sintering parameters which can be reflected also on the microstructure. The high entropy composite was completely alloyed after 40 hours of milling. The obtained composite was pressed using different pressures values in order to investigate the pressure influence on the microhardness and microstructure. The samples were investigated using optical microscopy, scanning electron microscopy, X-rays diffraction and microhardness tests. The microhardness values for all the samples were between 300 – 700 HV.

Studies on Friction and Mechanical Properties of High Density Polypropylene (HDPP) Filled with Modified Talc

2012 ◽  
Vol 624 ◽  
pp. 279-282
Author(s):  
Feng Zhan ◽  
Nan Chun Chen
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Lamellar Structure ◽  
Testing Machine ◽  
High Density ◽  
Impact Testing ◽  
Wear Testing ◽  
Frictional Surface ◽  
Universal Testing ◽  
Scanning Electron

Talc was modified by aluminate coupling agent (ACA) before filling it into high density polypropylene (HDPP) to prepare talc/HDPP composites. Scanning electron microscopy (SEM), wear testing machine, electronic universal testing machine, and impact testing machine were used to analyze the surface modification and the effects of modified talc on friction and mechanical properties of modified talc/HDPP composites. The results indicate that after modified the lamellar structure of talc particles are open and the dispersion of particles are improved, and the edges and corners of surface become softer. Friction properties indicate that when the talc content is 8 wt%, both µ and K are at a lower value, which show that have better wear resistance. The frictional surface is relatively smooth and no furrow trace has found. Mechanical properties show that with talc content increasing, tensile strength and flexural strength of composites increase.

Synthesis and Characterization of Red Mud and Sawdust Based Geopolymer Composites as Potential Construction Material

2018 ◽  
Vol 923 ◽  
pp. 130-134 ◽  
Author(s):  
Ing Kong ◽  
Kay Min Khoo ◽  
Oliver Buddrick ◽  
Abdul Aziz Baharuddin ◽  
Pooria Khalili
Keyword(s):  
Compressive Strength ◽  
Red Mud ◽  
Raw Materials ◽  
Construction Material ◽  
Testing Machine ◽  
Industrial Wastes ◽  
Sem Images ◽  
Universal Testing ◽  
Geopolymer Composites

The aim of this study was to synthesize the geopolymer composites formed by two industrial wastes, namely red mud (RM) and saw dust (SD). SD was chemically treated with alkali for the removal of lignin and subsequently bleached, before forming composite with acid-modified RM. The composites were then characterized by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetic analysis (TGA) and universal testing machine to study the morphology, chemical, thermal and mechanical properties. The FTIR spectrum showed that Si and Al from the raw materials played the major role in forming aluminosilicate geopolymer composites. The SEM images revealed that SD and RM particles aggregated to form fully condensed geopolymer matrices with high compressive strength of 8.3-138 MPa, which were comparable to Portland cement (compressive strength of 9-20.7 MPa).

scholarly journals Reconditioning of self-ligating brackets

2011 ◽  
Vol 82 (1) ◽  
pp. 158-164 ◽  
Author(s):  
Maria Francesca Sfondrini ◽  
Esmeralda Xheka ◽  
Andrea Scribante ◽  
Paola Gandini ◽  
Giuseppe Sfondrini
Keyword(s):  
Statistical Analysis ◽  
Bond Strength ◽  
Null Hypothesis ◽  
Shear Bond Strength ◽  
Testing Machine ◽  
Shear Mode ◽  
Universal Testing ◽  
Adhesive Remnant Index ◽  
Significant Difference ◽  
Scanning Electron

Abstract Objective: To test the null hypothesis that there is no significant difference in the shear bond strength (SBS) and Adhesive Remnant Index (ARI) scores of new vs reconditioned self-ligating brackets. Materials and Methods: One hundred and twenty permanent extracted bovine teeth were embedded in resin blocks. Three different new and reconditioned self-ligating orthodontic brackets (Smart Clip [3M Unitek]; Quick [Forestadent]; and Damon3MX [Ormco]) were tested. Scanning electron microphotographs of the different new (groups 1, 3, and 5) and reconditioned (groups 2, 4, and 6) bracket bases were taken before starting the experiments. Brackets were then bonded to the teeth using an orthodontic adhesive and were then tested in shear mode using an Instron Universal Testing Machine. ARI scores were then recorded. Statistical analysis was performed to determine significant differences in SBS and ARI Scores. Results: Smart Clip and Damon3MX reconditioned brackets showed significantly lower SBS than did new ones. On the contrary, Quick reconditioned brackets showed significantly higher SBS than did new ones. No significant differences in ARI scores were found after the reconditioning process for the three different brackets tested. Conclusion: The in-office reconditioning procedure alters the SBS of self-ligating brackets, although SBS values still remain clinically acceptable.

Uniformly Structured Methyltrimethoxysilane-Based Silica Aerogels with Enhanced Mechanical Property by Surfactant-Free Fabrication

2019 ◽  
Vol 19 (03) ◽  
pp. 1950017
Author(s):  
Yutie Bi ◽  
Jiayi Zhu ◽  
Zikai Xie ◽  
Hongbo Ren
Keyword(s):  
Contact Angle ◽  
Failure Strain ◽  
Testing Machine ◽  
Three Dimensional ◽  
Silica Aerogels ◽  
Water Contact ◽  
Molar Ratios ◽  
Universal Testing ◽  
Superhydrophobic Property ◽  
Scanning Electron

The uniformity, elasticity and hydrophobicity of methyltrimethoxysilane (MTMS)-based silica aerogels, which were prepared by using dimethyl sulfoxide (DMSO) as the solvent, were investigated. The as-prepared silica aerogels were characterized by means of scanning electron microscope, Fourier transform infrared, contact angle/interface system and electronic universal testing machine. The hydrophobicity of the MTMS-based silica aerogels could be adjusted by tuning the MTMS/DMSO molar ratios. The water contact angle of the MTMS-based silica aerogels could be as high as 160.2∘, suggesting its superhydrophobic property. It was found that all the MTMS-based silica aerogels had the typical three-dimensional porous structure. The failure strain of MTMS-based silica aerogels could be as high as 66.14%.

Preparation and properties of LGF/ER/TPU/PMMA composites

2015 ◽  
Vol 22 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Jianbing Guo ◽  
Daohai Zhang ◽  
Huiju Shao ◽  
Kaizhou Zhang ◽  
Bin Wu
Keyword(s):  
Mechanical Properties ◽  
Thermoplastic Polyurethane ◽  
Testing Machine ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical ◽  
Universal Testing ◽  
Long Glass Fiber ◽  
Scanning Frequency ◽  
Morphology And Mechanical Properties ◽  
Scanning Electron

AbstractA series of long glass fiber (LGF)-reinforced epoxy resin (ER), thermoplastic polyurethane (TPU) elastomers, and poly(methyl methacrylate) (PMMA) composites were prepared by using self-designed impregnation device. Dynamic mechanical properties of the LGF/ER/TPU/PMMA composites have been investigated by using dynamic mechanical thermal analysis (DMA). The results indicated that the content of PMMA and TPU and scanning frequency had important influence on dynamic mechanical properties and glass transition of the LGF/ER/TPU/PMMA composites. In addition, the Arrhenius relationship has been used to calculate the activation energy of α-transition of the LGF/ER/TPU/PMMA composites. The thermal properties of the LGF/ER/TPU/PMMA composites were studied by thermogravimetric analysis (TGA). Morphology and mechanical properties of the composites are investigated by scanning electron microscopy (SEM), a universal testing machine, and a ZBC-4 Impact Pendulum.

Microstructures and Phase Formation of Refractory MoNbTaVZr High Entropy Alloy

2020 ◽  
Vol 993 ◽  
pp. 384-390
Author(s):  
Hao Yu Wang ◽  
Zi Yue Wang ◽  
Zhi Sheng Nong ◽  
Ji Jie Wang ◽  
Tian Nan Man ◽  
...  
Keyword(s):  
Cast Alloy ◽  
Testing Machine ◽  
High Entropy Alloy ◽  
Chemical Compositions ◽  
X Ray ◽  
Component Distribution ◽  
High Entropy ◽  
Unknown Phase ◽  
Universal Testing ◽  
Second Phases

Microstructures, component distribution and mechanical properties of a refractory high entropy alloy MoNbTaVZr were investigated by scanning electron microscope, X-ray diffractometer and universal testing machine, and the formation rule of second phases in as-cast alloy was discussed by the results of first principle calculations. The results show that as-cast MoNbTaVZr alloy is composed of two solid solutions with body centered cubic structure, together with Mo2Zr and an unknown phase. The chemical compositions of dendritic regions are relatively uniform, while Zr and V elements are rich in interdendritic regions. There is a short yielding phase when as-cast alloy was operated by the compression. According to calculations, the C15 Mo2Zr Laves phase with the strongest formation ability and highest structural stability would be formed preferentially in MoNbTaVZr refractory high entropy alloy.

Thermophysical and Mechanical Properties of Carbonated Hydroxyapatite

2012 ◽  
Vol 512-515 ◽  
pp. 989-993 ◽  
Author(s):  
Qing Xia Zhu ◽  
Wei Hui Jiang ◽  
Chuan Shao ◽  
Yi Bao
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Sintering Temperature ◽  
Testing Machine ◽  
Carbonate Content ◽  
Flexure Strength ◽  
Carbonated Hydroxyapatite ◽  
Universal Testing ◽  
Calcination Method ◽  
Scanning Electron

The carbonated hydroxyapatite (CHA) was synthesized by precipitation-calcination method. The influences of carbonate subsitution on high-temperature sintering, thermal expansion coefficient (CET) and flexural strength were investigated by the high-temperature dilatometer, scanning electron microscopy (SEM) and universal testing machine. The results showed that the sintering temperatures of CHA were related to the initial carbonate contents. The sintering temperature decreased with increasing initial carbonate contents. The CET of CHAs decreased with the increase of carbonate content, due to the stoma caused by the partially decompostion of CHAs. The CHA ceramics tested were as strong in flexure strength when compared to non-carbonated hydroxyapatite.

Effect of Aluminum Addition on AlxCoFeMnNiZn Multi-Component Production

2017 ◽  
Vol 751 ◽  
pp. 53-59 ◽  
Author(s):  
Amnart Suksamran ◽  
Nawarat Worauaychai ◽  
Nattaya Tosangthum ◽  
Thanyaporn Yodkaew ◽  
Rungtip Krataitong ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Melting Process ◽  
Core Shell ◽  
High Entropy Alloys ◽  
Dendritic Solidification ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Entropy ◽  
Core Shell Structure ◽  
Scanning Electron

Five multi-component alloy (MCA) formulations of CoFeMnNiZn (MCA01), Al0.5CoFeMnNiZn (MCA02), Al1.0CoFeMnNiZn (MCA03), Co5Fe5Mn30Ni20Zn40 (MCA04) and Al8.4Co4.6Fe4.6Mn27Ni18.4Zn37 (MCA05) were prepared by mechanical alloying and melting process (MAM). Five-component alloys of MCA01-MCA05 were designed using empirical formulae for high entropy alloys. Phase formation and microstructure were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that MCA01 was partially melted by MAM process. However, MCA02-MCA05 could be melted and cast by MAM process. The microstructures of as-cast MCA02 and MCA03 showed dendritic solidification. Nevertheless, the as-cast MCA04 showed microstructure similar to that of Ni-based superalloy, i.e., the as-cast MCA04 consisted of γ matrix and γ′ phase. Moreover, egg type core shell structure was found in the interdendritic regions of the MCA05 alloy. In addition, the Al-added MCA02 and MCA03 alloys showed crystal structures of FCC1, FCC2 and BCC. MCA04 alloy demonstrated crystal structure of FCC whereas MCA05 alloy had crystal structures of FCC and Primitive Cubic.

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