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Tungsten carbide

M Jacinta Santos, Heleine Maria Chagas Rêgo, Leticia Linares, Amin S Rizkalla, Gildo C Santos
OBJECTIVE: To compare the effect of surface finishing and polishing protocols on the surface roughness (Ra) of methacrylate-based and silorane-based resin composites. METHODS AND MATERIALS: Fifty specimens (5 mm x 2 mm) of each composite material were prepared using a split mold: Filtek™ Supreme Ultra (3M ESPE), Tetric EvoCeram® (Ivoclar Vivadent), Tetric Ceram™ HB (Ivoclar Vivadent), and Filtek™ LS Low Shrink (3M ESPE). Specimens were divided into five groups (n = 10) according to the following procedures: G1 - 15-µm fine diamond bur (FDB); G2 - 15-µm FDB followed by a 20-fluted tungsten carbide bur; G3 - 15-µm FDB followed by diamond-impregnated micropolishing points (D-FINE Double Diamond Polishing System, Clinician's Choice); G4 - 15-µm FDB followed by diamond-impregnated micropolishing points (Flame Point Pre-polisher and Shine, Brassseler USA); and G5 - 15-µm FDB followed by the application of a surface sealer (PermaSeal®, Ultradent Products, Inc...
November 2017: Compendium of Continuing Education in Dentistry
Xin Tang, Kit H Bowen, Florent Calvo
Tungsten oxide cluster anions (WO3)3(-) produced from a magnetron source were soft-landed on highly oriented pyrolytic graphite (HOPG) surfaces at different temperatures, and the structures formed upon deposition were analyzed using ex situ atomic force microscopy. Under liquid nitrogen cooling conditions of 100 K, the clusters form small branched nanostructures extending over a few nanometers with a height not exceeding 1 nm. At 673 K, nanowires approximately 100 nm long and less than 10 nm in diameter are observed...
November 15, 2017: Physical Chemistry Chemical Physics: PCCP
Prashanthi Sampath Madhyastha, Shreya Hegde, N Srikant, Ravindra Kotian, Srividhya Sriraman Iyer
Background: Surface roughness associated with improper finishing/polishing of restorations can result in plaque accumulation, gingival irritation, surface staining, and poor esthetic of restored teeth. The study aimed to evaluate the efficiency of various finishing and polishing systems and time using various procedures on surface roughness of some esthetic restorative materials. Materials and Methods: In this in vitro study, samples of two composite materials, compomer and glass ionomer cement (GIC) materials, were fabricated...
September 2017: Dental Research Journal
Stiven Forti, Antonio Rossi, Holger Büch, Tommaso Cavallucci, Francesco Bisio, Alessandro Sala, Tevfik Onur Menteş, Andrea Locatelli, Michele Magnozzi, Maurizio Canepa, Kathrin Müller, Stefan Link, Ulrich Starke, Valentina Tozzini, Camilla Coletti
This work reports an electronic and micro-structural study of an appealing system for optoelectronics: tungsten disulfide (WS2) on epitaxial graphene (EG) on SiC(0001). The WS2 is grown via chemical vapor deposition (CVD) onto the EG. Low-energy electron diffraction (LEED) measurements assign the zero-degree orientation as the preferential azimuthal alignment for WS2/EG. The valence-band (VB) structure emerging from this alignment is investigated by means of photoelectron spectroscopy measurements, with both high space and energy resolution...
November 2, 2017: Nanoscale
Jiaqing Xie, Tianfeng Zhou, Benshuai Ruan, Yifei Du, Xibin Wang
To study the effects of the interface thermal resistance on surface morphology evolution in precision glass molding (PGM) for microlens array with different mold materials, including Tungsten carbide and heat-resistant stainless steel, the glass-mold interface thermal resistance is calculated, and heat-transfer simulation of PGM based on an interface thermal resistance model at the heating stage is conducted correspondingly. The effect of flattening behavior on the glass-mold interface is explained. Then, experiments evaluating the relationship between heating time and glass surface roughness are carried out, and the glass adhesion phenomenon appearing on the heat-resistant stainless steel mold is observed and analyzed...
August 10, 2017: Applied Optics
Samar Reda Al-Sayed Ali, Abdel Hamid Ahmed Hussein, Adel Abdel Menam Saleh Nofal, Salah Elden Ibrahim Hasseb Elnaby, Haytham Abdelrafea Elgazzar, Hassan Abdel Sabour
Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy...
October 15, 2017: Materials
Gregory W Wilson, Alex E Hay
The short-pulse acoustic backscatter amplitude calibration technique of Dragonette, Numrich, and Frank [(1981), J. Acoust. Soc. Am. 69, 1186-1189] is evaluated for MHz frequency systems, as are used to measure environmental suspended sediment concentration. The technique involves measuring backscatter from a short transmit pulse reflected by a solid spherical target, and treating the first received reflection as equivalent to that from a perfectly rigid sphere. In this implementation, the target sphere is 16 mm diameter tungsten carbide...
September 2017: Journal of the Acoustical Society of America
Jothi Raamahlingam Rajaran, Abd Jabar Nazimi, Rama Krsna Rajandram
Surgical removal of impacted mandibular third molar is a routine procedure in oral surgery. Various iatrogenic complications related to the procedure has been discussed well in the literatures before. Some of these complications are related to the wrong usage of instruments and techniques. Here we discuss a rare complication on a 42-year-old male, related to the use of high-speed handpiece drill in mandibular third molar removal in a general dental office setting. He was referred when a high speed tungsten carbide bur was accidentally broken and displaced into the mandibular bone during surgical procedure...
September 27, 2017: BMJ Case Reports
Ming-Sheng Wang, Yong Cheng, Longze Zhao, Ujjal K Gautam, Dmitri Golberg
The interaction between graphene and various metals plays a central role in future carbon-based device and synthesis technologies. Herein, three different types of metal nanoelectrodes (W, Ni, Au) were employed to in situ study the graphene-metal interfacial kinetic behaviors in a high-resolution transmission electron microscope. The three metals exhibit distinctly different interactions with graphene when driven by a heating current. Tungsten tips, the most carbon-starved ones, can ingest a graphene sheet continuously; nickel tips, less carbon starved, typically "eat" graphene only by taking a "bite" from its edge; gold, however, is nonactive with graphene at all, even in its molten state...
October 24, 2017: ACS Nano
Samantha M Schmuecker, Dale Clouser, Theodore J Kraus, Brian M Leonard
Transition metal carbides including chromium, molybdenum, and tungsten are of particular interest as renewable energy catalysts due to their low cost and abundance. While several single metal carbide systems form multiple phases with different compositions and crystal structures, most of these materials are not as well studied due to their limited synthetic approaches and instability. By taking advantage of a low temperature salt flux synthetic method, these unique phases can be more easily synthesized and separated as phase pure materials...
October 10, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Weiqing Zheng, Liang Wang, Fei Deng, Stephen A Giles, Ajay K Prasad, Suresh G Advani, Yushan Yan, Dionisios G Vlachos
Proton conductivity of the polymer electrolyte membranes in fuel cells dictates their performance and requires sufficient water management. Here, we report a simple, scalable method to produce well-dispersed transition metal carbide nanoparticles. We demonstrate that these, when added as an additive to the proton exchange Nafion membrane, provide significant enhancement in power density and durability over 100 hours, surpassing both the baseline Nafion and platinum-containing recast Nafion membranes. Focused ion beam/scanning electron microscope tomography reveals the key membrane degradation mechanism...
September 4, 2017: Nature Communications
Huihuang Fang, Junmou Du, Chenchen Tian, Jianwei Zheng, Xinping Duan, Linmin Ye, Youzhu Yuan
Evenly dispersed tungsten carbides with controlled phase compositions that exhibit an impressive capacity to carry out the regioselective hydrogenolysis of inert aryl ether C-O bonds instead of aliphatic C-O bonds to produce aromatic compounds are reported.
September 14, 2017: Chemical Communications: Chem Comm
József Szalma, László Vajta, Edina Lempel, Ákos Tóth, Sára Jeges, Lajos Olasz
PURPOSE: The aim of this in vitro study was to investigate temperature increases in the inferior alveolar canal (IAC), when different bone preparation methods approximate and penetrate the IAC. MATERIALS AND METHODS: In pig mandible, buccal bone removals were performed until the neurovascular bundle became visible. Temperatures were registered with thermocouple probes and with infrared thermometer. Preparations were performed with diamond drills (DD), tungsten carbide drills (TCD), piezoelectric diamond sphere (PT_D) and saw (PT_S) tips, and a combined preparation method was also performed whereby the superficial three-fourths of the bone was removed with TCD and the deepest one-fourth of the bone with PT_D (TCD + PT_D_7 °C) or PT_S (TCD + PT_S_7 °C), using cooled irrigation (7 °C)...
October 2017: Journal of Cranio-maxillo-facial Surgery
Bo Sun, Yong Sun, Chengxin Wang
Due to the coexistence of metal- and ionic-bonds in a hexagonal tungsten carbide (WC) lattice, disparate electron behaviors were found in the basal plane and along the c-axial direction, which may create an interesting anisotropic mechanical and electrical performance. To demonstrate this, low-dimensional nanostructures such as nanowires and nanosheets are suitable for investigation because they usually grow in single crystals with special orientations. Herein, we report the experimental research regarding the anisotropic conductivity of [0001] grown WC nanowires and basal plane-expanded nanosheets, which resulted in a conductivity of 7...
November 3, 2017: Nanotechnology
Aurélien Henry, Peter Hesemann, Johan G Alauzun, Bruno Boury
MxOy and MxOy/C composites (M=V, Fe and W) were obtained by mineralization of cellulose with several metal chlorides. Cellulose was used both as a templating agent and as an oxygen and a carbon source. Soluble chloride molecules (VOCl3 and WCl6) and a poorly soluble ionic chloride compound (FeCl3) were chosen as metal oxide precursors. In a first time, primary metal oxide/cellulose composites were obtained via a thermal treatment by reacting urea impregnated filter paper with the corresponding metal chlorides in an autoclave at 150°C after 3days...
October 15, 2017: Carbohydrate Polymers
Maurício Barbieri Mezomo, Juliana Abreu, Juliana Weber, Renato Dalla Porta Garcia, José Antônio Poli Figueiredo, Eduardo Martinelli de Lima
INTRODUCTION: The aim of this in vitro study was to compare the temperature rises in the pulp chamber and time spent with different techniques for orthodontic resin adhesive removal. METHODS AND MATERIALS: Adhesive removal was performed in 20 extracted human maxillary second premolars with five techniques: high-speed tungsten carbide burs with water-cooling (BurH-cool) and without cooling (BurH), low-speed carbide burs (BurL), low-speed aluminum-oxide discs (DiscL), and low-speed fiberglass burs (BurFGL)...
2017: Iranian Endodontic Journal
Narguess Nemati, Mansoor Bozorg, Oleksiy V Penkov, Dong-Gap Shin, Asghar Sadighzadeh, Dae-Eun Kim
A novel functional multilayer coating with periodically stacked nanolayers of amorphous carbon (a:C)/ tungsten carbide (WC) and an adhesion layer of chromium (Cr) was deposited on 304 stainless steel using a dual magnetron sputtering technique. Through process optimization, highly densified coatings with high elasticity and shear moduli, excellent wear resistance, as well as minimal susceptibility to corrosive and caustic media could be acquired. The structural and mechanical properties of the optimized coatings were studied in detail by a variety of techniques...
August 14, 2017: ACS Applied Materials & Interfaces
Meng Li, Youhong Sun, Qingnan Meng, Haidong Wu, Ke Gao, Baochang Liu
A metal-based matrix is usually used for the fabrication of diamond bits in order to achieve favorable properties and easy processing. In the effort to reduce the cost and to attain the desired bit properties, researchers have brought more attention to diamond composites. In this paper, Fe-based impregnated diamond composites for drill bits were fabricated by using a pressureless infiltration sintering method at 970 °C for 5 min. In addition, boron was introduced into Fe-based diamond composites. The influence of boron on the density, hardness, bending strength, grinding ratio, and microstructure was investigated...
December 12, 2016: Materials
Andy Nieto, Lin Jiang, Jaekang Kim, Dae-Eun Kim, Julie M Schoenung
Nanodiamonds (ND) present a unique combination of desirable mechanical, functional, and chemical characteristics that are ideally suited for reinforcing and enhancing the wear resistance of carbide based materials. Tungsten carbide cobalt (WC-Co) matrix nanocomposites reinforced with varying amounts of ND (2 - 10 vol.%) were synthesized here by spark plasma sintering. The rapid thermal consolidation route enabled attainment of dense samples with a significant retention of the metastable diamond phase. NDs affected the microstructural evolution, chemistry, and mechanical properties of WC-Co...
August 1, 2017: Scientific Reports
Peng Jia, Lei Chen, Jiancun Rao, Yujin Wang, Qingchang Meng, Yu Zhou
Zirconium carbide (ZrC) reinforced tungsten (W) composite was hot-pressed at 2200 °C for 1 h in vacuum, which was subsequently heat treated in the temperature range of 2200 to 2500 °C for 1.5 or 2 h. The relative ratios of ZrC phase were 21.0, 23.3 and 25.9 mol.% for the mixture of starting powders, composites sintered for 1 h and solid-solution treated at 2500 °C for 1.5 h, respectively. The solid solubility of W in ZrC increased with the increment in heat-treating temperature and time to a maximum value of 18...
July 26, 2017: Scientific Reports
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