Showing 13 results for Carbide
N. Zarrinfar and A. Saidi,
Volume 21, Issue 2 (1-2003)
Abstract
Titanium carbide is used as an attractive reinforcement to produce particulate metal matrix composites. One of the problems to use this carbide as a reinforcement in copper-based composites is the lack of wetability in Cu-TiC system. This property improves as the C/Ti ratio in carbide decreases.
Problems to use this carbide as a reinforcement in copper-based composites is the lack of wetabiity in Cu-TiC system. This property improves as the C/Ti ratio in carbide decreases.
A practical method is presented in this paper to improve the dispersion of titanium carbide into liquid copper and emphasis is placed on the C/Ti ratio in the carbide. It was observed that the C/Ti ratio in a raw mixture containing only Ti and C was equal to C/Ti ratio in the carbide after synthesis but when copper powder was added to the raw materials, this ratio was higher than the starting value. Regarding the relationship between the titanium carbide lattice parameter and the C/Ti ratio in the carbide and this ratio in the raw mixture, a graph was drawn that related the C/Ti=1, a network of agglomerated TiC particles with the same C/Ti ratio is formed which cannot be dispersed into liquid copper. When this ratio is decreased to 0.3, particulate titanium carbide with C/Ti=0.5 can be easily dispersed into liquid copper.
Keywords: SHS reaction, titanium carbide
M. Shamanian, A. Saatchi, M. Salehi and T. H North,
Volume 21, Issue 2 (1-2003)
Abstract
The metallurgical and mechanical properties of Ti6Al4V/(WC-Co) friction welds have ben investigated. The microstructure close to the bondline comprised a mixture of acicular and equiaxed α plus β phases. The diffusion of elements in the welded specimens has been detected. The fracture strengths of Ti6Al4V/(WC-Co) friction welds markedly improved when the cobalt content in the (WC-Co) carbide substrate increased.
During the three-point bend testing of Ti6Al4V/WC-6wt.%Co welds, the crack initiated at the bondline region at the periphery of the weld and then propagated into the brittle (WC-6wt.%Co) substrate, while with the Ti6Al4V/WC-11 wt.%Co and Ti6Al4V/WC-24wt.%Co welds, the crack initiated and propagated at the bondline region.
Keywords: Friction welding, Ti6Al4V alloy, Cemented tungsten carbide, Microstructure, Fracture strength
N. Setoudeh, A. Saidi, A. Shafyei and N.j. Welham,
Volume 27, Issue 2 (1-2009)
Abstract
P. Safaie, G. H. Borhani, S. R. Bakhshi,
Volume 33, Issue 1 (7-2014)
Abstract
In this study, pure powders such as molybdenum, silicon, aluminum and titanium carbide were utilized to produce MoSi2 compound, MoSi2 /20 Vol % TiC composite, MoSi2-x Al alloyed compound and MoSi2-x Al/20 Vol % TiC alloyed composite. The initial powders were mixed in specified ratios, and then, were activated by mechanical milling. Milled powders were compacted, synthesized and sintered in the temperature range of 1100 -1400 oC. SEM was used to investigate the microstructural change and XRD for identification of phases. Effect of aluminum addition on phase formation was investigated. Addition of aluminum by over 9 atomic percent resulted in the formation of Mo(Si,Al)2 in alloyed matrix.
R. Tajalli, H. Baharvandee, H. Abdizadeh,
Volume 33, Issue 3 (3-2015)
Abstract
In this research, ZrC nano particles were synthesized by self-propagating high temperature (SHS) using the mixed powder of ZrO2-C-Mg and NaF or NaCl diluent. The effect of different proportions of raw materials, milling time, composition
of the diluent and also pickling on the synthesis of ZrC was investigated. Optimal amounts of magnesium and sodium fluoride for the synthesis of ZrC were 2.8 and 2 mol, respectively. Milling process of 120 minutes decreased the diffusion gap of raw material and increased the combustion reaction progress. XRD and SEM analysis showed that the NaF diluent more than NaCl caused a reduction in the size of the particles of ZrC and increased the progress of the combustion reaction. Synthesized samples were subjected to pickling in order to remove impurities of MgO by 37% HCl, and distilled water was used to wash off NaF and NaCl residues. ZrC particle size of different samples were in the range of 50-90 nm.
N. Zakeri, S. Otroj, M.r. Saeri,
Volume 34, Issue 3 (12-2015)
Abstract
In this study, the effect of nano-titania addition on the mechanical strength of mullite-bonded alumina-siliconcarbide nano-composites was investigated. To this end, the gel-casting process via nano-silica sol was used for shaping the nano-composite.The firing temperature of composition was determined by use of STA. The compressive and bending strengths of samples were measured after firing at 1300 °C. Besides, the physical properties, phase composition and microstructure of the composites were evaluated after firing. The results showed that the use of nano-titania up to 1 wt.% had a higher effect on improvement of nano-composite mechanical strength. The nano-titania addition led to increasing of mullite phase and higher growth of its needle-like grains. Enhancing of ceramic bonds between grains and the improvement of mechanical strength were obtained by increasing the mullite phase.
S. Torkian, A. Shafyei, M.r. Toroghinejad, M. Safari,
Volume 35, Issue 3 (12-2016)
Abstract
In this paper the effect of deep cryogenic treatment time on microstructure and tribological behavior of AISI 5120 case hardennig steel is studied. The disk shape samples were carburized at 920 ◦C for 6 hours and air cooled; after austenitizing, the samples were quenched in oil.Then immediately after quenching and sanding, the sample were kept in liquid nitrogen for 1, 24, 30 and 48 h and then tempered at 200 ◦C for 2 hours. The wear test was done by ball on disk method using of WC ball at 80 and 110 N load. For characterization of carbides, the etchant solution of CuCl2 (5 gr)+HCl (100 mL) + ethanol (100 mL) was used. The hardness of samples before and after of tempering was measured by vicers method at 300 N load.. The amount of retained austenite was measured by X Ray Diffraction method. For 1DCT and 24DCT samples it was about 8% and 4%; in the other samples, the retained austenite peal was so decreased that it was not visible. The result showed that the hardness increases by deep cryogenic treatment in all speciments. While wear resistance increases in 1DCT and 24DCT samples, it decreases for 30DCT and 48DCT samples in compare with Conventional heat treatment (CHT) sample in both applied loads, such that , 48DCT sample has the least wear resistance. The cause of increament of hardness is due to reduction in amount of retained austenite as a result of deep cryogenic treatment and decreasing in wear resistance after 24 hour, is due to carbide growth and nonhemogenuse distribution in microstructure and then weakening of matrix. So the 24 hour deep cryogenic treatment was the best optimal for AISI 5120 steel.
M. Mottaghi, M. Ahmadian,
Volume 36, Issue 1 (6-2017)
Abstract
In this research, the wear behavior of commercial grades of WC-10wt%Co (H10F), WC-40vol%Co and WC-40vol%FeAl-B composites with different amounts of boron from zero to 1000 ppm has been investigated by the pin on disk test method at high temperature. The wear tests were done under load of 40 N, a distance of 100 m and at ambient temperature, 200 ̊C and 300 ̊C. Wear surfaces were examined by scanning electron microscopy. The results showed that the wear resistance of all composites decreased with increasing temperature. The boron free WC-40vol%FeAl composite showed the lowest wear resistance at all ranges of temperature. In the presence of boron up to 500 ppm in iron-aluminide matrix, the high temperature wear resistance of these composites improves and the wear mechanisms changes from particle pullout into abrasive state. The toughness enhancement of these composites and plasticity enhancement of iron aluminide in the presence of boron, leads to better link of the interface of FeAl matrix and tungsten carbide particles, and thus increases the wear resistance of these composites. WC-40vol% FeAl-500ppmB composite has a higher wear resistance at high temperature than WC-40vol% Co and commercial WC-10wt% Co.
A. Panahi Moghadam, M. Seifollahi, S. M. Abbasi, S. M. Ghazi Mirsaeed,
Volume 37, Issue 2 (9-2018)
Abstract
This paper was concerned with the effect of Mg on the temperature mechanical behavior and evaluation of the microstructure. The results showed that with increasing Mg from 0 to 47 ppm, the grain size was reduced from 64 to 38 µm and the carbides volume fraction was raised from 2.2 to 4.6 vot%. Mg changed the morphology of the carbide from a coarse and continuous one to a separate one. Mg with the mechanisms of grain boundary and matrix/carbide boundary led to changing the carbide composition and also, the mechanical properties. Mg increment from 0 to 47 ppm caused the enhancement of yield strength and rupture life from 309 to 345 MPa and from 16h to 30h, respectively. Grain size and the amount of carbide were the main factors contributing to the rupture of life properties in this study. The increment of the carbide volume fraction was the main mechanism of rupture life enhancement.
M. Samii Zafarghandi, S. M. Abbasi,
Volume 38, Issue 2 (9-2019)
Abstract
In the present work, hot tensile behavior of Haynes 25 Co-base alloy was investigated in the temperature range of 950-1200 ˚C and 0.1 s-1. Thermodynamic calculations showed that M23C6 and M6C carbides were stable below 1000 ˚C and above 1050 ˚C, respectively. Stress-strain curves also indicated an unusual trend of strain fracture. It was observed that with increasing temperature from 950 to 1050 ˚C, the fracture strain was decreased, while it was raised above 1050 ˚C again. Increasing the volume fraction of M6C carbide rich in Tungsten resulted in the loss of ductility. Also, microstructural evaluations showed dynamic recrystallization (DRX) grains were nucleated and growth was around carbides and the initial grains at 1150 ˚C. Occurrence of DRX led to the improvement of ductility via grain refinement mechanism, so this alloy had the highest level of ductility at 1150 ˚C
A. R. Parvanian, H. R. Salimijazi, M. H. Fathi,
Volume 38, Issue 4 (1-2020)
Abstract
The concentrated solar power (CSP) is one of the renewable energy sources in which solar irradiation heat energy will be used in a steam turbine to generate electrical grid. Solar radiation is absorbed by a solar receiver reactor on the surface of a porous solar absorber. In this survey, synthesis and mechanical/thermal characterization of micro-porous silicon carbide (SiC) absorber to be used in solar reactor is carried out. SiC foams were synthesized and categorized based on three different pore sizes i.e. 5, 12 and 75 ppi. Mechanical behavior and thermal shock resistance of porous foams in the working temperature range for absorber (25-1200 °C) were evaluated. Results revealed that the specific compressive strength (σc/ρ) of foams increase exponentially by a decrement in the porosity percentage and the average pore size. Moreover, for foams with smaller pore size, a considerable decrease in mechanical strength due to thermal shock was observed. This could be due to increase in the number of struts per unit volume i.e. more weak struts to withstand the mechanical loading. So, porous foams with coarser pore sizes were distinguished to be more capable of tolerating thermal shock while serving as solar absorbers.
O. Ganji, S.a. Sajjadi, M. Mirjalili, Z.g. Yang,
Volume 40, Issue 4 (3-2022)
Abstract
Carbide coatings, due to their excellent anti-wear properties, are used to extend the life of molds exposed to abrasion forces. Various processes have been applied to produce carbide coatings. Thermo-reaction diffusion (TRD) using a molten salt bath could be considered as an economical method compared to other coating processes. In this study carbide-composite coatings using molten salt baths composed of oxides of carbide forming elements (chromium and vanadium) on SKD-11 and T10 tool steels at 1000 ℃ were formed. The results showed that the coatings included chromium carbide phases: CrC, Cr7C3, and Cr23C6 as well as vanadium carbide: VC, VC0.88, V6C5, V8C7, and a triple phase with the composition of Cr2C2V. The highest hardness (1890-2020 HV) and the lowest coefficient of friction (0.14) were achieved by the carbide coating of T10 steel with the second bath of vanadium oxide.
H. Fallah-Arani, N. Riahi-Noori, S. Baghshahi, A. Sedghi, F. Shahbaz Tehrani,
Volume 40, Issue 4 (3-2022)
Abstract
In this research, the effect of addition of silicon carbide (SiC) nanoparticles on the improvement of the structural, superconductivity, magnetic, and flux pinning properties of high-temperature superconductor Bi1.6Pb0.4Sr2Ca2Cu3O10+θ (Bi-2223) was investigated. The Bi-2223 ceramic superconductor was prepared using the sol-gel method, and silicon carbide nanoparticles were modified by Azobisisobutyronitrile (AIBN). The X-ray diffractometry, feild emission scanning electron microscopy, magnetic susceptibility, and hystersis loop measurements were performed to characterize the synthesized compounds. Based on the magnetic measurements, the superconductivity transition temperature dropped with an increase in the content of nanoparticles. Also, the maximum magnetization, hysteresis loop width, critical current density, and magnetic flux pinning force belonged to the sample with 0.4 wt.% SiC nanoparticles.
