Effect Of Silicon Content Research Articles

Effects of silicon content on the microstructure and corrosion behavior of Fe–Cr–C hardfacing alloys

Three Fe-based alloys, namely 55Fe39Cr6C, 49Fe39Cr6C6Si, and 45Fe39Cr6C10Si (wt.%), were fabricated on AISI St52 using a tungsten-inert gas (TIG) heat source. Microstructure, microhardness, and electrochemical corrosion behavior of the TIG clad composite coatings were investigated. It was found that as-deposited coatings consisted of higher volume fractions of carbides (Cr 7C 3). Potentiodynamic polarization studies in the 3.5 wt.% NaCl solution showed that the corrosion resistance of the substrate was remarkably improved by TIG surface coating (TSC) with 55Fe39Cr6C and 49Fe39Cr6C6Si, while 45Fe39Cr6C10Si had a lower effect on this same property. The formation of silicides (Fe 3Si) in the clad with 45Fe39Cr6C10Si was taken as the reason for the reduced corrosion resistance observed as compared to those of the other clads.

Effects of Silicon Content and Intercritical Annealing on Manganese Partitioning in Dual Phase Steels

Steels of constant manganese and carbon contents with silicon content of 0.34% – 2.26% were cast. The as-cast steels were then hot rolled at 1100 °C in five passes to reduce the cast ingot thickness from 80 to 4 mm, air cooled to room temperature and cold rolled to 2 mm in thickness. Dual phase microstructures with different volume fraction of martensite were obtained through the intercritical annealing of the steels at different temperatures for 15 min followed by water quenching. In addition to intercritical annealing temperature, silicon content also altered the volume fraction of martensite in dual phase steels. The partitioning of manganese in dual phase silicon steels was investigated using energy-dispersive spectrometer (EDS). The partitioning coefficient, defined as the ratio of the amounts of alloying element in the austenite to that in the adjacent ferrite, for manganese increased with increasing intercritical annealing temperature and silicon content of steels. It was also found that the solubility of manganese in ferrite and austenite decreased with increasing intercritical temperature. The results were discussed by the diffusivity and the solubility of manganese in ferrite and austenite existed in dual phase silicon steels.

Effect of silicon content on the microstructure and properties of Fe–Cr–C hardfacing alloys

In this study, the surface of St52 steel was alloyed with preplaced powders 55Fe39Cr6C, 49Fe39Cr6C6Si, and 45Fe39Cr6C10Si using a tungsten-inert gas as the heat source. Following surface alloying, conventional characterization techniques, such as optical microscopy, scanning electron microscopy, and X-ray diffraction were employed to study the microstructure of the alloyed surface. Microhardness measurements were performed across the alloyed zone. Room-temperature dry sliding wear tests were used to compare the coatings in terms of their tribological behavior. It was found that the as-deposited coatings contained higher volume fractions of carbides (Cr7C3). The presence of 6%Si in the preplaced powders caused an increase in microhardness and wear resistance.

Formula Derivation and Application for Carbon Content versus Heating Temperature in Austenitizing of Cast Iron

In this paper, a formula for the calculation of the carbon content during the austenitizing of cast iron was deduced, considering the effect of silicon content upon the heat-treatment parameter. According to this formula, the carbon content of the austenite at a certain austenization temperature for a cast iron with given components can be easily calculated, and the austenization temperature required to give the expected carbon content in the austenite can also be determined. Moreover, according to the relationship between the austenization temperature Tx and the associated carbon content Cax,, and considering the effect of the silicon content, a diagram showing Cax, Tx and the silicon content during the austenitizing of cast iron was prepared.

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF HYPEREUTECTIC Al-Si/AlNp COMPOSITE

Hypereutectic Al - Si alloys with fine and evenly distributed Si precipitates have superior mechanical properties In this study, hypereutectic Al - Si alloy powders which contained 15 and 20wt% Si were prepared by a gas atomization process. 1, 3 and 5wt% AlN particles were blended with the Al - Si alloy powders using turbular mixer. The mixture was consolidated by Hot Press at 550°C for 1h under 60MPa. Relative density of the sintered samples was about 98% of theoretical density. This study was investigated by two ways. One is the effect of reinforcement weight fraction and the other is the effect of Silicon contents on the mechanical properties of the composite. Microstructural characterization and phase evaluation were carried out using X-ray Diffraction, Scanning Electron Microscopy equipped with Energy Dispersive Spectrometer. The results showed that the smaller the reinforcement particle size was and the better its distribution was, the higher ultimate tensile strength and hardness were.

Effect of silicon content on the sintering and biological behaviour of Ca 10(PO 4) 6-x(SiO 4) x(OH) 2-x ceramics

Silicated hydroxyapatite powders (Ca 10(PO 4) 6- x (SiO 4) x (OH) 2- x ; Si x HA) were synthesized using a wet precipitation method. The sintering of Si x HA ceramics with 0 ⩽ x ⩽ 1 was investigated. For 0 ⩽ x ⩽ 0.5, the sintering rate and grain growth decreased slightly with the amount of silicate. For larger amounts, the sintering behaviour differed with the formation of secondary phases before total densification. Sintering parameters (temperature and time) were adjusted to each composition to produce dense materials having similar microstructure without formation of these secondary phases. Dense ceramics made of pure hydroxyapatite and Si x HA containing various amounts of silicate (up to x = 0.6) were biologically tested in vitro with human osteoblast-like cells. The proliferation of cells on the surface of the ceramics increased up to 5 days of culture, indicating that the materials were biocompatible. However, the silicon content did not influence the cell proliferation.

Effect of Silicon Content on The High Temperature Oxidation of Ti-Si Alloys

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The Effect of Silicon Content on Impact Toughness of T91 Grade Steels

The impact resistance of silicon (Si)-containing modified 9Cr-1Mo steels has been investigated within a temperature regime of −40 to 440 °C using the Charpy method. The results indicate that the energies absorbed in fracturing the tested specimens were substantially lower at temperatures of −40, 25, and 75 °C compared to those at elevated temperatures. Lower impact energies and higher ductile-to-brittle-transition-temperatures (DBTTs) were observed with the steels containing 1.5 and 1.9 wt.% Si. The steels containing higher Si levels exhibited both ductile and brittle failures at elevated temperatures. However, at lower temperatures, brittle failures characterized by cleavage and intergranular cracking were observed for all four tested materials.

Effects of Si and its content on the scale formation on hot-rolled steel strips

The effect of silicon content (0.01–1.91 wt.%) on the oxidation kinetics and the structure of scales formed on silicon steels was investigated. A Thermal Gravimetric Analyzer (TGA) was used to measure the weight changes of various steels oxidized in dry air in the temperature range of 700–1000 °C. The results showed that both oxidation rate and scale thickness decreased with increasing silicon content in the steels. The scales that were formed on plain carbon steel and contained 0.51 wt.% Si mainly consisted of Fe 2O 3, Fe 3O 4, and Fe 1− X O. A scale with banded oxide structure was also observed in the steel containing 0.51 wt.% Si. For the steel containing 1.14 wt.% Si, a scale with two distinct layers of oxides was found. The outer layer was Fe 2O 3 while the inner layer of the oxide contained a high amount of Si. The scale of the steel containing 1.91 wt.% Si was much thinner. Beneath the outer Fe 2O 3 layer, an oxide enriched with Si and Al was found at the scale/substrate interface, which improved the passivity of the steel. Nodular scale formation resulting from local breakdown of the oxide was found on some discrete surface spots, particularly for the steel containing 1.91 wt.% Si. Internal oxidation was also observed in the high Si-containing steels.

Effect of Silicon Content over Fe-Cu-Si/C Based Composite Anode for Lithium Ion Battery

Two different anode composite material s comprising of Fe, Cu and Si prepared using high energy ball milling(HEBM) were explored for their capacity and cycling behaviors. Prepared powder composites in the ratioCu:Fe:Si = 1:1:2.5 and 1:1:3.5 were characterized through X-Ray diffraction (XRD) and scanning electronmicroscope (SEM). Nevertheless, the XRD shows absence of any new alloy/compound formation upon ballmilling, the elements present in Cu(1)Fe(1)Si(2.5)/Graphite composite along with insito generated Li

Effects of Silicon Content on the Mechanical Properties and Lubricated Wear Behaviour of Al–40Zn–3Cu–(0–5)Si Alloys

In this work, one ternary Al–40Zn–3Cu and seven quaternary Al–40Zn–3Cu–(0.25–5)Si alloys were synthesized by permanent mould casting. Their microstructure, mechanical and lubricated wear properties were investigated using appropriate test apparatus and techniques. As the silicon content increased the hardness of the alloys increased, but their elongation to fracture decreased. Tensile strength of the alloys decreased with increasing silicon content following a sharp decrease and a slight increase. Among the silicon-containing quaternary alloys the highest and the lowest tensile strength values (348 and 305 MPa) were obtained with the Al–40Zn–3Cu–2Si and Al–40Zn–3Cu–5Si alloys, respectively, while the base alloy (Al–40Zn–3Cu) exhibited a tensile strength of 390 MPa. However, the volume loss due to wear of the alloys increased with increasing silicon content after showing an initial increase and a sharp decrease. The lowest wear loss was obtained with the alloy containing approximately 2% Si which has the highest tensile strength among the quaternary alloys containing more than 0.25% Si. Wear surfaces of the alloys were characterized mainly by smearing indicating that adhesion is the dominant wear mechanism for the experimental alloys.

Effect of silicon content on wear resistance and corrosion behaviour of Al–Si eutectic alloy

In the present study, Al–Si eutectic alloys produced at the Aluminium Institution were studied. The alloys were cast and forged into bars of 20 mm diameter. The results obtained were compared with a pure aluminium sample. Metallographic analysis, spectral analysis, SEM and energy dispersive spectroscopy analysis, pin on disk abrasive wear tests and mass loss tests were performed. Wear resistances of alloys with various silicon contents were tested under different loads and constant abrasive speed. SiC abrasive paper of 80 grit size was used. The dry sliding tests were carried out under loads of 10, 20 and 30 N and the testing was conducted under a constant sliding velocity of 36˙8 m min–1 in a dry air atmosphere. Corrosion rates were determined in 0˙1M NaCl acid solutions. The corrosion tests were performed at 2, 4, 6 and 8 h. The wear and corrosion resistance of all the eutectic alloys increased with increasing silicon content in the matrix.

Role of silicon in solidification microstructure in hot-dipped 55 wt% Al–Zn–Si coatings

An experimental study has been carried out into the effect of silicon content on 55 wt% Al–Zn–Si metallic coating solidification. Immersion experiments were conducted on a metal coating simulator, and the resulting solidification structure was characterised in terms of spangle size and secondary dendrite arm spacing (SDAS). It was found that at bath temperatures of 600 °C as silicon content was increased from 1.05 to 1.5 wt% there were an increase in spangle size without any change in SDAS. Thermodynamic modelling was utilised to probe the phase stability of intermetallic species in the baths. Two competing intermetallic phases, α-AlFeSi and Fe 3Al, are stabilised dependant upon bath silicon content and temperature. Literature data for the lattice mismatch between α-Al, the primary solidification phase in this study, with these two intermetallic phases indicates that FeAl 3 has much better crystallographic fit than does α-AlFeSi. This supports the proposal that FeAl 3 has a higher nucleation site density for solidification, which results in a reduced spangle size. The thermodynamic modelling has been used to provide compositional and temperature ranges for spangle size control.

The effect of silicon content on long crack fatigue behaviour of aluminium–silicon piston alloys at elevated temperature

The microstructure of aluminium piston alloys comprises primary and eutectic silicon together with numerous intermetallics. Previous research has shown that primary silicon strongly influences both fatigue crack initiation and subsequent propagation behaviour, however, the detailed effects of varying silicon volume fraction and morphology have not been fully addressed. Therefore, the fatigue properties of a number of candidate piston alloys with varying volume fractions of silicon have been studied. Long crack fatigue tests have been performed at room and elevated temperature typical of the gudgeon pin boss (200 °C) using a test frequency of 15 Hz (a typical engine frequency at engine idle condition). Microstructural characterisation using image analysis approaches combined with optical profilometry has been used to assess the fracture surfaces of test samples. The role of primary Si in enhancing crack growth rates at high Δ K levels, whilst affording improvements in crack growth rates at lower Δ K levels due to local crack deflections and shielding, has been confirmed. In the absence of primary Si (lower Si content alloys) the low Δ K level crack growth behaviour is dominated by matrix properties (intra-dendritic crack growth pre-dominates) whilst the high Δ K level crack growth behaviour is inter-dendritic and occurs along the weak path of the eutectic Si and/or intermetallic network.

Effects of silicon content on the microstructural features and mechanical and sliding wear properties of Zn–40Al–2Cu–(0–5)Si alloys

In this study, one ternary zinc–aluminium–copper and eight quaternary zinc–aluminium–copper–silicon alloys were produced by permanent mould casting. The friction and wear properties of the alloys were investigated using a block-on-disc machine. The results obtained from these investigations were explained in terms of microstructure and mechanical properties of the alloys and compared with those obtained from SAE 660 bronze under the same test conditions. The microstructure of the ternary Zn–40Al–2Cu alloy consisted of aluminium-rich α, zinc-rich η and copper-rich ɛ phases while the quaternary Zn–40Al–2Cu–(0.5–5)Si alloys revealed silicon particles in addition to the phases observed in the ternary alloy. The silicon particles showed a homogeneous distribution in the alloys containing up to 2.5% Si. However, when the silicon content exceeded this level, silicon particles gave rise to microsegregation in the alloys by gathering in some areas as separate groups. The hardness and tensile strength of the Zn–40Al–2Cu–(0.5–5)Si alloys increased with increasing silicon content up to 2.5% Si, above which these values decreased as the silicon content increased. It was found that the coefficient of friction of the alloys decreased with increasing silicon content up to 1% Si. However, above this level, it increased as the silicon content increased. It was also found that the volume loss due to wear of the alloys decreased with increasing silicon content up to 2.5%, above which it increased as the silicon content increased. All the Zn–40Al–2Cu–(0–5)Si alloys were found to be much superior to the SAE 660 bronze as far as their tribological properties are concerned and among them, the best wear performance was obtained with the Zn–40Al–2Cu–2.5Si alloy.

Influence of silicon content on ion nitriding of ultrahigh strength steels

The effect of silicon content on the tempering behaviour and ion nitriding of ultrahigh strength AISI 4340 steels has been investigated. Four alloys with varying silicon contents were quenched and tempered for 1, 3, and 5 h, and ion nitrided at different temperature and time conditions. The nitrided layers were characterised by microhardness tests, optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). An increase in silicon content enhanced tempering resistance of the steels and also significantly improved the hardness of the nitrided layers. The increase in silicon content produced thinner compound layers with better hardness. XRD analysis indicated a mixture of nitrides in these layers, γ-Fe4N, ϵ-Fe2-3N, CrN, MoN, and Si3N4, with their proportions varying with nitriding conditions.

The effect of silicon content on the microstructure and creep behavior in die-cast magnesium AS alloys

The effect of increasing levels of silicon on the microstructure and creep properties of high-pressure die-cast Mg-Al-Si (AS) alloys has been investigated. The morphology of the Mg2Si phase in die-cast AS alloys was found to be a function of the silicon content. The Mg2Si particles in castings with up to 1.14 wt pct Si have a Chinese script morphology. For AS21 alloys with silicon contents greater than 1.4 wt pet Si (greater than the alpha-Mg2Si binary eutectic point), some Mg2Si particles have a coarse blocky shape. Increasing the silicon content above the eutectic level results in an increase in the number of coarse faceted Mg2Si particles in the microstructure. Creep rates at 100 hours were found to decrease with increasing silicon content in AS-type alloys. The decrease in creep rate was most dramatic for silicon contents up to 1.1 wt pct. Further additions of silicon of up to 2.64 wt pct also resulted in significant decreases in creep rate.

Effects of silicon content on the mechanical and tribological properties of monotectoid-based zinc–aluminium–silicon alloys

In this work, one binary zinc–aluminium and eight ternary zinc–aluminium–silicon alloys were produced by permanent mould casting. Friction and wear properties of the alloys were investigated in both as-cast and heat-treated conditions using a block-on-ring machine and the results were related to their microstructure and mechanical properties. It was observed that the microstructure of the zinc–aluminium–silicon alloys consisted of aluminium-rich α, zinc-rich η phases and silicon particles. The size and distribution of silicon particles were found to be dependent on the silicon content of the alloys. The heat treatment involving quench-ageing removed the dendritic microstructure of the alloys and produced a fine-grained microstructure, but had no significant effect on the silicon particles. Silicon additions were found to be very effective on mechanical and wear properties of zinc-based alloys. The hardness and the tensile strength of the alloys increased with increasing silicon content up to 2 wt.% Si, above which it decreased as the silicon content increased further. It was also found that friction coefficient and wear rate of the alloys decreased with increasing silicon content up to 2 wt.% Si, but above this level they increased as the silicon content increased further. Among the alloys tested, the highest tensile strength and wear resistance was obtained with the Zn–40Al–2Si alloy. It was also observed that the wear behaviour of the Zn–Al–Si alloys correlates strongly with their hardness, tensile strength and friction coefficient.

Effect of Si Content on the Creep Properties of Ti-6Al-4Fe-xSi Alloys

Effect of silicon content on the creep properties of Ti-6Al-4Fe-xSi was studied. Creep resistance of Ti-6Al-4Fe-xSi alloys was superior to that of Ti-6Al-4V. Ti-6Al-4Fe-0.5Si alloy exhibited the highest rupture strength and creep resistance among the Ti-6Al-4Fe-xSi alloys investigated. The minimum creep rate of the alloys decreased with increasing silicon content up to 0.5wt.% and then it increased again when the silicon content was higher than 0.5wt.%. TiFe precipitates were formed mainly at the β phase area of Ti-6Al-4Fe-xSi alloys by consuming titanium and iron in β phase, when the alloys were thermally exposed at 500 and 600°C during the creep test. During the creep test, microvoids were induced at the TiFe/α phase interfaces and the cracks were formed along the TiFe/α phase interfaces by the coalescence of the voids. Those cracks were finally connected each other through the α phase.

熱間工具鋼の窒化組織とシリコン量,窒化前組織の関係

熱間工具鋼の窒化組織とシリコン量,窒化前組織の関係