1,757 results match your criteria vickers hardness

A novel CAD/CAM resin composite block with high mechanical properties.

Dent Mater 2021 Apr 10. Epub 2021 Apr 10.

Glidewell Dental, Irvine, CA, USA.

Objective: To determine the mechanical properties of a newly-developed CAD/CAM resin composite block and compare with other resin composite blocks and a polymer-infiltrated ceramic block.

Methods: Experimental composite block was formulated by our proprietary resin and filler technologies and cured via Hot Isostatic Pressing (HIP). Bar-shaped specimens (1 × 4×12 - 13 mm, n = 10) for flexural strength, flexural modulus and modulus of resilience were sectioned from block materials and measured in accordance to modified ISO-6872. Read More

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Adjunctive procedure with solvent mixtures in non-surgical endodontic retreatment: does it affect root dentin hardness?

Odontology 2021 Apr 2. Epub 2021 Apr 2.

Faculty of Dental Medicine, CINTESIS, University of Porto, Porto, Portugal.

The aim of this study was to compare the effects of new irrigation solvent mixtures with Methyl ethyl ketone (MEK)/Tetrachloroethylene (TCE) and MEK/Orange oil (OOil), and different agitation techniques on dentin hardness. One hundred forty-four mandibular teeth were prepared and standardized, with each root's middle part transversely sectioned. Initial hardness was measured using a Vickers microhardness tester. Read More

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Surface Integrity of Dimethacrylate Composite Resins with Low Shrinkage Comonomers.

Materials (Basel) 2021 Mar 26;14(7). Epub 2021 Mar 26.

Department of Biomaterials Science and Turku Clinical Biomaterials Center-TCBC, Institute of Dentistry, University of Turku, 20520 Turku, Finland.

The goal of current research was to investigate the influence of adding low shrinkage "Phene" like comonomers hexaethylene glycol bis(carbamate-isoproply-α-methylstyrene) (HE-Phene) and triethylene glycol bis(carbamate-isoproply-α-methylstyrene) (TE-Phene) on the surface and color characteristics of composite resin. A range of weight fractions (0, 10, 20, 30, 40 wt.%) of HE/TE-Phene monomers were mixed with bisphenol A glycidyl methacrylate (GMA)/triethylene glycol dimethacrylate (TEGDMA) monomer. Read More

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On the Use of EBSD and Microhardness to Study the Microstructure Properties of Tungsten Samples Prepared by Selective Laser Melting.

Materials (Basel) 2021 Mar 4;14(5). Epub 2021 Mar 4.

Laser College of Engineering, Beijing University of Technology, Beijing 100124, China.

Additively manufactured tungsten and its alloys have been widely used for plasma facing components (PFCs) in future nuclear fusion reactors. Under the fusion process, PFCs experience a high-temperature exposure, which will ultimately affect the microstructural features, keeping in mind the importance of microstructures. In this study, microhardness and electron backscatter diffraction (EBSD) techniques were used to study the specimens. Read More

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Fracture Analysis of High-Strength Screw for Highway Construction.

Materials (Basel) 2021 Mar 25;14(7). Epub 2021 Mar 25.

Department of Marketing, Oleg Balatskyi Academic and Research Institute of Finance, Economics and Management, Sumy State University, 2 Rymskogo-Korsakova St., 40007 Sumy, Ukraine.

High-strength screws represent one of the main joining or fastening components which are commonly used in the process of installation of frame constructions for information boards or signposts, relating to the traffic roads. The control of the production process may not always be a sufficient method for ensuring road safety. The backward investigation and control of the screw material processing seems to be the one of the most important procedures when there is the occurrence of any failure during the operation of the screw. Read More

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Approaches to the Mechanical Properties of Threaded Studs Welded to RHS Columns.

Materials (Basel) 2021 Mar 15;14(6). Epub 2021 Mar 15.

Department of Construction and Manufacturing Engineering, University of Oviedo, 33203 Gijón, Spain.

The use of Rectangular Hollow Sections (RHS) as columns in steel construction includes important advantages like higher mechanical strength and fire resistance. However, the practical demountable bolted joints between beams and columns are not easy to execute, due to impossibility of access to the inner part of the tube. The use of threaded studs welded to the face of the tube and bolted to the beam by means of angle cleats is one of the cheaper and most efficient solutions to obtain beam-column joints with a semi-rigid behavior, as is usually sought in building structures. Read More

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A Novel Approach by Spark Plasma Sintering to the Improvement of Mechanical Properties of Titanium Carbonitride-Reinforced Alumina Ceramics.

Molecules 2021 Mar 3;26(5). Epub 2021 Mar 3.

Łukasiewicz Research Network-Cracow Institute of Technology, Centre of Advance Manufacturing Technology, 73 Zakopianska St., 30-418 Cracow, Poland.

Ti(C,N)-reinforced alumina-zirconia composites with different ratios of C to N in titanium carbonitride solid solutions, such as Ti(C,N) (C:N = 30:70) and Ti(C,N) (C:N = 50:50), were tested to improve their mechanical properties. Spark plasma sintering (SPS) with temperatures ranging from 1600 °C to 1675 °C and pressureless sintering (PS) with a higher temperature of 1720 °C were used to compare results. The following mechanical and physical properties were determined: Vickers hardness, Young's modulus, apparent density, wear resistance, and fracture toughness. Read More

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PICN Nanocomposite as Dental CAD/CAM Block Comparable to Human Tooth in Terms of Hardness and Flexural Modulus.

Materials (Basel) 2021 Mar 3;14(5). Epub 2021 Mar 3.

Division of Biomaterials, Department of Oral Functions, Kyushu Dental University, Fukuoka 803-8580, Japan.

Polymer infiltrated ceramic network (PICN) composites are an increasingly popular dental restorative material that offer mechanical biocompatibility with human enamel. This study aimed to develop a novel PICN composite as a computer-aided design and computer-aided manufacturing (CAD/CAM) block for dental applications. Several PICN composites were prepared under varying conditions via the sintering of a green body prepared from a silica-containing precursor solution, followed by resin infiltration. Read More

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Sustainable Additive Manufacturing: Mechanical Response of Polyethylene Terephthalate Glycol over Multiple Recycling Processes.

Materials (Basel) 2021 Mar 2;14(5). Epub 2021 Mar 2.

Mechanical Engineering Department, Hellenic Mediterranean University, 71410 Heraklion, Greece.

The continuous demand for thermoplastic polymers in a great variety of applications, combined with an urgent need to minimize the quantity of waste for a balanced energy-from-waste strategy, has led to increasing scientific interest in developing new recycling processes for plastic products. Glycol-modified polyethylene terephthalate (PETG) is known to have some enhanced properties as compared to polyethylene terephthalate (PET) homopolymer; this has recently attracted the interest from the fused filament fabrication (FFF) three-dimensional (3D) printing community. PET has shown a reduced ability for repeated recycling through traditional processes. Read More

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Experimental Investigation of Additive Manufacturing Using a Hot-Wire Plasma Welding Process on Titanium Parts.

Materials (Basel) 2021 Mar 7;14(5). Epub 2021 Mar 7.

Automation for Material Processing Research Team, Material Processing and Manufacturing Automation Research Group, National Metal and Materials Technology Center (MTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani 12120, Thailand.

In this paper, we propose hot-wire plasma welding, a combination of the plasma welding (PAW) process and the hot-wire process in the additive manufacturing (AM) process. Generally, in plasma welding for AM processes, the deposit grain size increases, and the hardness decreases as the wall height increases. The coarse microstructure, along with the large grain size, corresponds to an increase in deposit temperature, which leads to poorer mechanical properties. Read More

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Weldability of Underwater Wet-Welded HSLA Steel: Effects of Electrode Hydrophobic Coatings.

Jacek Tomków

Materials (Basel) 2021 Mar 11;14(6). Epub 2021 Mar 11.

Division of Welding Engineering, Faculty of Mechanical Engineering and Ship Technology, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland.

The paper presents the effects of waterproof coatings use to cover electrodes on the weldability of high-strength, low-alloy (HSLA) steel in water. With the aim of improving the weldability of S460N HSLA steel in water, modifications of welding filler material were chosen. The surfaces of electrodes were covered by different hydrophobic substances. Read More

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Fluorescence and physical properties of thulium and erbium co-doped dental zirconia.

Dent Mater J 2021 Mar 27. Epub 2021 Mar 27.

Institute of Scientific and Industrial Research, Osaka University.

The fluorescence and physical properties of thulium and erbium co-doped dental zirconia were investigated. The high-translucency yttria-stabilized dental zirconia specimens co-doped with TmO powder 0.8 wt% and ErO powder at proportions from 0. Read More

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Enhanced Hardness in Transition-Metal Monocarbides via Optimal Occupancy of Bonding Orbitals.

ACS Appl Mater Interfaces 2021 Mar 18;13(12):14365-14376. Epub 2021 Mar 18.

College of Science, Institute of Functional Materials, and State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620, China.

An efficient strategy that can guide the synthesis of materials with superior mechanical properties is important for advanced material/device design. Here, we report a feasible way to enhance hardness in transition-metal monocarbides (TMCs) by optimally filling the bonding orbitals of valence electrons. We demonstrate that the intrinsic hardness of the NaCl- and WC-type TMCs maximizes at valence electron concentrations of about 9 and 10. Read More

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Mechanical Analysis of Explanted Telescopic Rods in the Management of Osteogenesis Imperfecta: A Multicenter Study.

J Pediatr Orthop 2021 Mar 17. Epub 2021 Mar 17.

Department of Orthopaedics, Sheffield Children's Hospital Department of Engineering, Sheffield Hallam University, Sheffield Department of Orthopaedics, Great Ormond Street Hospital Institute of Child Health, Great Ormond Street Hospital, London Bristol Royal Hospital for Children, Bristol, UK.

Background: Telescopic rods in the management of osteogenesis imperfecta fail frequently. This could be attributed to technical errors, rod design, and rod structure. We aimed to analyze the mechanical properties and tribology of explanted male and female components to identify effects of in vivo telescoping that may relate to observed patterns of successful telescoping or failure. Read More

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Influence of radiant exposure values from two third generation LED curing units on polymerization profile and microhardness of orthodontic composite under ceramic and metallic brackets.

Dental Press J Orthod 2021 10;26(1):e2119150. Epub 2021 Mar 10.

Universidade Estadual de Ponta Grossa, Departamento de Odontologia (Ponta Grossa/PR, Brazil).

Introduction: Third generation of LED light curing units might be used in short exposure periods for orthodontic brackets bonding.

Objective: This study evaluated the effect of the different radiant exposure (RE) values: Manufacturers' instructions (MI), ½ MI, 1/4 MI and Turbo mode. Two third-generation LED curing units were used: VALO® and Bluephase 20i® . Read More

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Sonofragmentation of Organic Molecular Crystals vs Strength of Materials.

J Org Chem 2021 Mar 15. Epub 2021 Mar 15.

Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 60801, United States.

Mechanochemistry, the interface between the chemical and the mechanical worlds, includes the relationship between the chemical and mechanical properties of solids. In this work, fragmentation of organic molecular crystals during ultrasonic irradiation of slurries has been quantitatively investigated. This has particular relevance to nucleation processes during sonocrystallization, which is increasingly used in the processing and formulation of numerous pharmaceutical agents (PAs). Read More

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Mechanical Properties and Synthesis of Nanocrystalline Ta - 1.67Al₂O₃ Composite by Pulsed Current Activated Heating.

J Nanosci Nanotechnol 2021 Jul;21(7):4042-4045

Division of Advanced Materials Engineering, The Research Center of Hydrogen Fuel Cell, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea.

Mixtures of Ta₂O and Al nanopowders were prepared using high energy ball milling method. Nanocrystalline Ta - 1.67Al₂O₃ composite was simultaneously synthesized and densified by pulsed current activated combustion synthesis method in a short time from mechanically activated mixtures of Ta₂O and Al powders. Read More

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Preparation of Hexagonal SrMnO₃ High-Quality Target for Magnetron Sputtering.

J Nanosci Nanotechnol 2021 Jul;21(7):4005-4010

Dept. Electrical Engineering, Gachon University, 1342 Seongnamdaero, Seongnam, 13120, Republic of Korea.

In recent years, the optical behavior of complex oxides are being increasingly used in light-harvesting applications. Perovskites are promising candidates for photovoltaic, photocatalytic, and optoelectric applications because of tunable band gaps and other unique properties such as fer-roelectricity To study the optical behavior of ferromagnetic-ferroelectric oxides, SrMnO₃ (SMO₃) targets intended for use in magnetron sputtering were prepared using SrCO₃ (99.99%) and Mn₂O₃ (99. Read More

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Sintered Characteristics of 3 Mole% Yttria-Stabilized Zirconia Polycrystals (3Y-TZP) Implants Manufactured by Slip-Casting and Computer Aided Design/Computer Aided Manufacturing (CAD/CAM).

J Nanosci Nanotechnol 2021 Jul;21(7):3877-3881

Department of Advanced Materials and Engineering, Chosun University, Gwangju 61452, Korea.

Two types of dense and toughened 3Y-TZP zirconia implants were fabricated by the sintering of green compacts. Then, the sintered properties of the two implants were compared. Slip-cast and post-sintered all-ceramic zirconia implants were fabricated by the heat treatment at 1450 °C for 2 h using optimal slurry conditions (60 wt% solid content, 1 wt% dispersant, and pH 12). Read More

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An ab-initio study on structural, elastic, electronic, bonding, thermal, and optical properties of topological Weyl semimetal TaX (X = P, As).

M I Naher S H Naqib

Sci Rep 2021 Mar 10;11(1):5592. Epub 2021 Mar 10.

Department of Physics, University of Rajshahi, Rajshahi, 6205, Bangladesh.

In recent days, study of topological Weyl semimetals have become an active branch of physics and materials science because they led to realization of the Weyl fermions and exhibited protected Fermi arc surface states. Therefore, topological Weyl semimetals TaX (X = P, As) are important electronic systems to investigate both from the point of view of fundamental physics and potential applications. In this work, we have studied the structural, elastic, mechanical, electronic, bonding, acoustic, thermal and optical properties of TaX (X = P, As) in detail via first-principles method using the density functional theory. Read More

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Evaluation of Resin Bonding to Tetragonal and Gradient-Shaded Cubic Zirconia Ceramics After Air-Abrasion.

J Nanosci Nanotechnol 2021 Sep;21(9):4959-4963

Department of Dental Biomaterials, School of Dentistry and Institute for Biomaterials Research & Development, Kyungpook National University, Daegu 41940, Republic of Korea.

Self-assembled nano-layering resulting from combined ionic and hydrogen-bonding interactions of phosphate functional monomers with zirconia have been proposed. The purpose of this study was to investigate the bond strengths of two phosphate monomer-containing adhesive resin cements (Panavia F 2.0 and RelyX U200) to a conventional tetragonal zirconia (Lava Plus, LP) and a new cubic zirconia (Lava Esthetic, LE), with three different shade zones, after air-abrasion. Read More

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September 2021

Microstructure and Sintering Behaviors of Al-Cr-Si (at.%) System Alloys Processed by Spark Plasma Sintering.

J Nanosci Nanotechnol 2021 Sep;21(9):4768-4772

Smart Mobility Materials and Components Groups, Korea Institute of Industrial Technology, 1110-9 Oryong-dong, Buk-gu, Gwangju 61012, Republic of Korea.

In this study, microstructure and sintering behaviors of the gas-atomized Al-(25 or 30) Cr-xSi alloy ( = 5, 10 and 20 at.%) during spark plasma sintering (SPS) process were investigated. Gas-atomized alloy powders were manufactured using Ar gas atomizer process. Read More

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September 2021

Enhancement of mechanical and corrosion resistance properties of electrodeposited Ni-P-TiC composite coatings.

Sci Rep 2021 Mar 5;11(1):5327. Epub 2021 Mar 5.

Department of Mechanical and Mechatronics Engineering, College of Engineering, Dhofar University, Salalah, Oman.

In the present study, the effect of concentration of titanium carbide (TiC) particles on the structural, mechanical, and electrochemical properties of Ni-P composite coatings was investigated. Various amounts of TiC particles (0, 0.5, 1. Read More

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Evaluation of tooth demineralization and interfacial bacterial penetration around resin composites containing surface pre-reacted glass-ionomer (S-PRG) filler.

Dent Mater 2021 Mar 3. Epub 2021 Mar 3.

Laboratory of Molecular and Preventive Dentistry, Department of Preventive Dentistry, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Huangpu District, Shanghai 200011, China. Electronic address:

Objective: To evaluate preventive effects of S-PRG-filled resin-composites on surrounding tooth demineralization and interfacial bacterial penetration.

Methods: Cavities were prepared on enamel or dentin blocks and treated by BeautiBond Universal (Shofu) and filled by resin-composites containing S-PRG filler (Shofu) at 0 wt% (P0, control), 10 wt% (P10), 30 wt% (P30), 50 wt% (P50) or 70 wt% (P70). The specimens were demineralized by Streptococcus mutans biofilms for 12 days. Read More

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Calcium Silicate-Based Biocompatible Light-Curable Dental Material for Dental Pulpal Complex.

Nanomaterials (Basel) 2021 Feb 27;11(3). Epub 2021 Feb 27.

Institute of Tissue Regeneration Engineering (ITREN), Dankook University, 119 Dandae-ro, Cheonan 31116, Chungcheongnam-do, Korea.

Dental caries causes tooth defects and clinical treatment is essential. To prevent further damage and protect healthy teeth, appropriate dental material is a need. However, the biocompatibility of dental material is needed to secure the oral environment. Read More

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February 2021

Impact of laser parameters on additively manufactured cobalt-chromium restorations.

J Prosthet Dent 2021 Feb 17. Epub 2021 Feb 17.

Professor and Dean, Faculty of Machine Building, Technical University of Cluj-Napoca, Cluj-Napoca, Romania.

Statement Of Problem: The selective laser melting (SLM) process has become popular for the fabrication of frameworks for metal-ceramic restorations, although their surface roughness is greater than with cast or milled frameworks. Limited information is available regarding the surface mechanical characteristics of cobalt-chromium (Co-Cr) SLM-manufactured restorations.

Purpose: The purpose of this in vitro study was to adapt the laser parameters for a remelting strategy, scanning the outer boundary of Co-Cr specimens, to reduce surface roughness and solidification defects, to determine microhardness, to investigate surface morphology and microstructure, and to establish surface mechanical characteristics. Read More

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February 2021

Neutron Bragg-edge transmission imaging for microstructure and residual strain in induction hardened gears.

Sci Rep 2021 Feb 18;11(1):4155. Epub 2021 Feb 18.

National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki, 305-0047, Japan.

A time-of-flight Bragg-edge neutron transmission imaging was used to investigate the microstructure and strain distributions in a gear hardened by a newly developed two-step induction-heating method: precursor (Sample 1) and final product (Sample 2). The edge-position and edge-broadening were determined and mapped with high spatial resolution, which enabled us to confirm the two-dimensional distributions of the microstructure and residual strain. A deep hardened layer was made for Sample 1 in which martensite was formed on the entire teeth and the outer peripheral portion of the gear body. Read More

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February 2021

Design of a Series of Metallic BN with Tunable Mechanical Properties.

J Phys Chem Lett 2021 Feb 17;12(7):1979-1984. Epub 2021 Feb 17.

Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.

Here a series of sp-sp BN ( = 1, 2, 3, 4, 5, 6) structures was constructed. These structures can be viewed as diamond-like BN blocks connected by single N-N bonds. Elastic constants and phonon dispersion curves confirm that all of the proposed structures are mechanically and dynamically stable. Read More

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February 2021

Tailoring Microstructure and Mechanical Properties of Additively-Manufactured Ti6Al4V Using Post Processing.

Materials (Basel) 2021 Jan 31;14(3). Epub 2021 Jan 31.

Materials Consultant, P.O. Box 7010, Shoham 6081668, Israel.

Additively-manufactured Ti-6Al-4V (Ti64) exhibits high strength but in some cases inferior elongation to those of conventionally manufactured materials. Post-processing of additively manufactured Ti64 components is investigated to modify the mechanical properties for specific applications while still utilizing the benefits of the additive manufacturing process. The mechanical properties and fatigue resistance of Ti64 samples made by electron beam melting were tested in the as-built state. Read More

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January 2021

Effect of Nb on Microstructure and Mechanical Property of Novel Powder Metallurgy Superalloys during Long-Term Thermal Exposure.

Materials (Basel) 2021 Jan 31;14(3). Epub 2021 Jan 31.

State Key Lab for Powder Metallurgy, Central South University, Changsha 410083, China.

Microstructure and mechanical properties of novel Ni-20Co-12Cr superalloys, with and without Nb addition, were systematically studied during long-term thermal exposure. With increased exposure time, the average diameter of the γ' precipitates increased in both alloys in succession; this is more obviously observed in alloy containing 1 wt% Nb (1Nb). It is suggested that Nb increased the γ' coarsening rate by accelerating the diffusion of Al and Nb in γ matrix. Read More

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January 2021