Effect Of Silicon Content Research Articles

Effects of silicon content and test conditions on the dry wear behaviour of Zn–30Al–3Cu–(0–5)Si Alloys

ABSTRACT Dry sliding wear performance of Zn-30Al-3Cu-(0-5)Si alloys was studied using a block-on-disc type test apparatus. Their microstructure consisted of β dendrites, α, η, and ϵ (CuZn4) phases, and silicon particles. Hardness and tensile strength of the alloys increased with silicon content but above 1% Si the trend reversed for the tensile strength. Total percent elongation, impact energy, compressive strength, and quality index of the alloys decreased with silicon content. However, the friction coefficient and wear volume showed different changes with silicon content, sliding distance, contact pressure, and sliding velocity. Worn surface examinations indicated that the wear of these alloys occurs by both abrasion and adhesion. Non-linear regression analysis showed that the friction coefficient and wear volume of the alloys can be calculated in terms of silicon content and either sliding distance or contact pressure and sliding velocity using the empirical equations developed in this work. Zn-30Al-3Cu-0.5Si alloy exhibited the highest quality index and wear resistance among the alloys tested. It was concluded that the hardness and tensile strength of the alloys containing hard and brittle phases have opposite effects on their dry wear behaviour. The wear volume of such alloys decreases with increasing hardness but increases with tensile strength.

Effect of silicon content on microstructure and mechanical properties of AlSi alloy coating obtained by physical vapour deposition

ABSTRACT Several contents of silicon in AlSi coatings, and substrate nature, were investigated in this present research. For this purpose, thin films were deposited by Physical Vapour Deposition onto three substrates: The effect of silicon content on the microstructure and mechanical properties of the coatings was studied. The microstructural observations showed that the coating carried out with 7 wt-%. silicon reduced the porosities by making the microstructures more homogeneous and denser. Also, the influence of substrate characteristics on the evolution and distribution of the microstructure formed during coating is important. Content of 13 wt-% eutectic enhanced the mechanical properties. The crystallite size evolves in a completely opposite way to that of the dislocation density and micro-deformation, with a minimum for the same values of silicon content (10–12 wt-%). The microstructural analysis allowed us to highlight the importance of silicon in the formation of intermetallic compounds.

Effect of Silicon Content in Al–Si Welding Wire on Mechanical Properties of Al/Cu Laser Welded Joint

Effect of Silicon Content in Al–Si Welding Wire on Mechanical Properties of Al/Cu Laser Welded Joint

Prediction of Wear Resistance of In-situ Zinc Matrix Composites Reinforced by Silicon Phase Based on Neural Network

Silicon phase reinforced zinc-aluminium alloy composites were prepared by in-situ method. The effect of silicon content and external load on the wear resistance of in-situ zinc--aluminium composites was studied by BP artificial neural network. The test results show that the silicon phase, as a hard material, plays the role of supporting load and improves the wear resistance of the alloy. With the increase of Si content, the wear resistance of in-situ zinc--aluminium composites increased first and then decreased. When the amount of silicon added exceeds 2.5-3%, the wear resistance will be reduced, which is related to the silicon phase aggregation and the easy separation of large silicon phases from the matrix. With the increase of external load, the relative wear continues to increase, which is related to the increase of friction. The neural network platform can successfully predict the general trend of wear resistance with the change of silicon content and load.

Effect of silicon content on the corrosion behaviors of CrAlSiN thin films deposited by magnetron co-sputtering

One CrAlN and four CrAlSiN thin films containing 0.8–7.3 at. % Si were grown by a magnetron co-sputtering process using pure Cr, Al, and Si targets. The microstructure of the CrAlSiN coating changed from a coarse columnar structure to a dense and compact morphology as Si content increased from 0.8 to 7.3 at. % due to the formation of more amounts of amorphous silicon nitride phase to block the growth of columnar grains. Pitting corrosion was the main corrosion failure mechanism for each coating. According to the potentiodynamic polarization test, the lowest corrosion current density, the highest pitting potential, and the widest passivation range were obtained on the 7.3 at. % Si contained CrAlSiN coating. After the electrochemical impedance spectroscopy study of CrAlN and CrAlSiN thin films in 3.5 wt. % NaCl aqueous solution for 100 h immersion, the corrosion resistance of CrAlSiN thin films was 14 times higher than the CrAlN film due to its fine nanocolumnar microstructure to effectively retard the attack of corrosive electrolyte through the defects of coating.

Low‐temperature reactive hot‐pressing of Ta0.2Hf0.8C–SiC ceramics at 1700°C

AbstractTemperature above 2000°C and additional pressure is generally required to achieve the full densification of TaxHf1−xC‐based ceramics. This work proposed a novel method to fabricate dense Ta0.2Hf0.8C ceramics at relatively low temperature. Using a small amount of Si as a sintering aid, Ta0.2Hf0.8C was densified at 1700°C by reactive hot‐pressing (RHP), with SiC formed in situ. Microstructure evolution mechanisms of the ceramics during RHP were investigated. The effect of silicon content on the densification and mechanical properties of the ceramics was revealed. It is indicated that the apparent porosity of the Ta0.2Hf0.8C–SiC ceramics was as low as 0.5%, whereas bending strength and fracture toughness of the ceramics were as high as ∼637 MPa and 6.7 MPa m1/2, respectively, when the silicon content was 8 wt.%. This work provides a new idea for the low‐temperature densification of TaxHf1−xC and other ultrahigh temperature ceramics with high performance.

Effect of Silicon Content on Microstructures and Properties of Directionally Solidified Fe-B Alloy.

In order to investigate the effect of Si content on the microstructures and properties of directionally solidified (DS) Fe-B alloy, a scanning electron microscope (SEM) with an energy dispersive spectrum (EDS), and X-ray diffraction have been employed to investigate the as-cast microstructures of DS Fe-B alloy. The results show that Si can strongly refine the columnar microstructures of the DS Fe-B alloy, and the columnar grain thickness of the oriented Fe2B is reduced with the increase of Si addition. In addition, Si is mainly distributed in the ferrite matrix, almost does not dissolve in boride, and seems to segregate in the center of the columnar ferrite to cause a strong solid solution strengthening and refinement effect on the matrix, thus raising the microhardness of the matrix and bulk hardness of the DS Fe-B alloy.

Cushioning effect of austenite in silicon stainless steels (SiSS) leading to improved wear resistance

The effect of silicon content (~2–6 wt%) on the wear behavior of a series of stainless steels is investigated using ball-on-disc wear test. The fractions of different phases and their deformation behavior considerably influence the wear behavior. The enhanced wear resistance of the steels with increased Si content is attributed to the improved hardness, increased fraction of ferrite phase, better strain hardening response, and grain refinement. Moreover, lenticular deformation of the austenite in the subsurface of worn-out zone parallel to the motion of the counter body (Si3N4 ball) serves cushioning effect by filling the cracks and preventing its growth during wear. This mainly attributes to the highest wear resistance in ~6 wt% Si-containing stainless steel.

Effect of silicon content on nucleation and growth of multiscale precipitates in Al–Mg–Si–Cu–Zn alloys for different aging paths

Controlling the precipitation evolution is an efficient strategy for optimization of those properties in Al–Mg–Si–Cu-(Zn) alloys. In this work, we have studied the precipitation evolution and mechanical behavior in Al–Mg–Si–Cu–Zn alloys with different aging routes and Si contents (0.55–1.08 wt%). The results reveal that multiscale precipitates can be formed under a certain aging route in Al–Mg–Si–Cu–Zn alloys, which can simultaneously improve the strength and elongation. Accordingly, the nucleation mechanism of multiscale precipitates in Al–Mg–Si–Cu–Zn alloys was put forward, which provides important guidance on designing the novel Al–Mg–Si–Cu–Zn alloys with high formability and rapid bake hardening response for automotive applications.

Effect of Silicon Content on Corrosion Resistance of a Cold Rolled Non-Oriented Silicon Steel

Effect of Silicon Content on Corrosion Resistance of a Cold Rolled Non-Oriented Silicon Steel

Effect of silicon content on the microstructure evolution, mechanical properties, and biocompatibility of β-type TiNbZrTa alloys fabricated by laser powder bed fusion

Beta-type titanium alloys are excellent candidates for biomedical applications because of their very low elastic modulus, excellent corrosion resistance, and biocompatibility. However, many traditional β-type titanium alloys exhibit low yield strength. In this study, a small amount of Si (3 and 5 at.%) was added to a Ti-35Nb-7Zr-5Ta (wt%, TNZT) biomedical alloy prepared via laser powder bed fusion (LPBF) to increase its yield strength. The Si addition resulted in a significant increase in the compression yield strength of the alloy (from 802 to 1282 MPa). Meanwhile, the elastic moduli of the TNZT alloys (48.7–60.6 GPa) with 3 and 5 at.% Si were much lower than that of the Ti-6Al-4 V alloy (110 GPa), which is used extensively in clinical applications. The microstructural analyses indicated that the ultrahigh-strength of the TNZT alloy containing Si was due to the presence of ultrafine (Ti, Nb, Zr)5Si3 (S1) grains in the β-Ti matrix. In addition, thin shell-shaped S1 and (Ti, Nb, Zr)2Si (S2) grains precipitated along the columnar β-Ti grain boundaries in the TNZT alloys containing 3 and 5 at.% Si, respectively. Moreover, the introduction of Si to the TNZT alloy significantly refined the grains, weakened the cubic texture, decreased surface roughness, and improved Vickers hardness. The ultrahigh strength of the Si-containing TNZT alloys was due to grain boundary strengthening and precipitation strengthening. In addition, in vitro studies with MC3T3-E1 cells revealed that the cytocompatibilities of the LPBF-fabricated TNZT and Si-containing TNZT alloys were equivalent and were better than that of the LPBF-fabricated Ti-6Al-4 V alloy. In particular, the TNZT alloy with 3 at.% Si showed the best elastic modulus (48.7 ± 1.0 GPa), yield strength (1151 ± 17 MPa), and cell biological response among all the alloys investigated in this study, and hence was found to be a suitable candidate for application in load-bearing bone implants.

Effects of silicon content on electrical resistivity and thermal conductivity of Al-Si binary alloys.

Effects of silicon content on electrical resistivity and thermal conductivity of Al-Si binary alloys.

Detect and Effects of Silicon Content in Chemical Composition of Steel Material After the Hot Dip Galvanized Coating

We are looking for permanent solutions to the problems based on global warming, which is one of the main agenda items of the world and our country; In the light of critical considerations such as sustainability, efficient use of resources, and prevention of waste; protection of steel from corrosion has become a obligation beyond necessity in order to protect and make sustainable the values produced by the increased use of steel. In this article, which includes the details of our study on the visual variability that occurs after the hot dip galvanizing process, which is widely used to protect the raw material resources of our world and the energy spent to bring these resources to the economy, and the determination of the silicon content after coating, The processes that it is involved in from corrosion to its separation from the structure and the results it causes are discussed.

Effect of Silicon Content on Mechanical Properties and Progressive Collapse Behavior of Closed-cell Aluminum Foams

Effect of Silicon Content on Mechanical Properties and Progressive Collapse Behavior of Closed-cell Aluminum Foams

Laser welding of dual-phase steels with different silicon contents: Phase evolutions, microstructural observations, mechanical properties, and fracture behavior

Abstract This paper reports an investigation into the effect of silicon content on phase transformations, microstructural evolutions, and mechanical behavior of Nd:YAG laser welded dual-phase steels. The experimental investigation was conducted on laboratory-processed 0.15 C-1.7 Mn steels with different silicon contents. The heat treatment cycle to develop a dual-phase structure consisted of austenitization at 790 °C for 15 min followed by water quenching. The fabricated steels were welded in a butt joint configuration to obtain a fully-penetrated weld joint. Optical microscopy, scanning electron microscopy, and uniaxial tensile test were performed to evaluate microstructural changes, phase transitions, and mechanical properties, respectively. The fracture behavior of the welded joints was also investigated using a scanning electron microscope. The results showed that the volume fraction of martensite was increased with an increase in silicon content. The samples with higher silicon content also had a finer structure, which was due to the higher driving force created during previous cold working. All welded joints were found to consist of a nearly fully martensitic structure, and the heat-affected zone (HAZ) contained a low-temperature region (with partially or fully tempered martensite) and a high-temperature region (with newly-formed martensite). The specimen with the lowest silicon content had the minimum elongation and toughness modulus owing to an incomplete tempering process in HAZ. The specimens containing higher amounts of silicon were fractured in the base metals because of the presence of the martensite phase as a major micro-constituent in the fusion zone. The fracture mechanism of the laser-welded dual-phase steels with a low-volume fraction of martensite and small ferrite grain size was micro-void formation whilst the separation and de-cohesion were observed in dual-phase steels that had a high-volume fraction of martensite.

Effect of silicon on oxidation behavior of 9Cr-ODS steel at 650 °C

The effect of silicon content on the evolution of oxide layer and oxides in Si-containing 9Cr-ODS steel during 5, 20 and 50 h oxidation was studied. The experiment was carried out at 650 °C in air. XRD was used to analyze oxide phase at different oxidation times. The morphology and elemental composition of the oxides were investigated by SEM/EDS. With the silicon content increasing, the oxidation resistance of ODS steel was improved. The oxide layer of 0.5 wt%Si specimen was mainly composed of Fe2O3, and the Mn-rich and Cr-rich oxides were found at oxidation 50 h. The Si-rich oxide layer was gradually generated in the 4 wt%Si specimen with the increase of the oxidation times. Meanwhile, a discontinuous Mn-rich and Cr-rich oxide layer was found on the surface of 4 wt%Si specimen steel after 50 h of oxidation. The reason is that the diffusion of Fe3+ was prevented by Si-rich oxide layer. Moreover, the diffusion rate of Cr and Mn was increased by a large amount of Si-doped. Consequently, the addition of Si is beneficial to the oxidation resistance of ODS steel.

Effect of Silicon Content on wear and Hardness of Al-Si Alloys

In the current work the Al-Si composite is prepared using stir casting method with variation in the percentage(4%, 6% and 8%) of the Si particles in it. stir casting method is one of the cheapest method for production of Al alloys. The prepared composites of different percentages of Si are investigated for it wears behaviour using Pin-on-Disk machine and other properties like hardness. Characterization of Worn surface of the composite is done using SEM. Among the metallic matrices, the aluminum-based matrix remains the most studied metal matrix material for the production of MMCs. This is largely due to the large variety of properties provided by aluminum-based matrix composites at low manufacturing costs. While many Metal Matrix Composites ( MMCs) are desirable for use in various industrial applications, Aluminum Matrix Composites ( AMCs) are the most commonly used in specialized applications because they combine reasonable strength, low density, durability, machinability, availability, performance and price. In aerospace applications, the excellent tribological characteristics of Al-Si and Al-Sn alloys have led to their widespread use, especially in plain bearings, cylinder liners and internal combustion pistons. It is seen that Si is uniformly distributed in the Al matrix and hardness increases to 71BHN with 8%Si in Al matrix. Further analysis revealed that the microstructure homogeneity of the samples is strongly affected its hardness and Wear rate decreases with increase in Si.

Effect of Silicon Content on the Decomposition of Austenite in 0.4C Steel during Quenching and Partitioning Treatment

Although quenched and partitioned (Q&P) steels are traditionally alloyed with Si, its precise role on microstructural mechanisms occurring during the partitioning process is not thoroughly investigated. In this study, a systematic investigation has been carried out to reveal the influence of Si on austenite decomposition, phase transformation and carbide precipitation during Q&P treatment. Using a Gleeble thermomechanical simulator, three medium carbon steels with varying Si contents (0.25, 0.70 and 1.5 wt.%) were hot-rolled, reaustenitized, quenched into the Ms -Mf range, retaining about 20% austenite at the quench-stop temperature (TQ), and held for 1000 seconds above TQ in the temperature range of 200-300°C in order to better understand the mechanisms operating during partitioning. Dilatometric measurements combined with microstructural characterization using SEM-EBSD, TEM, and XRD clearly revealed the occurrence of various mechanisms. The effect of partitioning temperature/time on the hardness of the Q&P samples was correlated with the microstructural features. Steel containing low Si content (0.25%) was incapable of promoting carbon enrichment of austenite during partitioning, leading to its continuous decomposition into isothermal martensite and/or bainite without any detectable austenite retained even holding at 300°C. In comparison, 1.5% Si content promoted retention of about 19% austenite under similar Q&P conditions. Small fractions of bainite and high-carbon martensite formed during final cooling in both steels after partitioning at 200°C. Moreover, carbide precipitation was strongly retarded by high Si content.

The effect of silicon content on liquid-metal-embrittlement susceptibility in resistance spot welding of galvanized dual-phase steel

Abstract Liquid metal embrittlement (LME) can have a significant effect on the mechanical properties of resistance spot welding (RSW) advanced high strength steels (AHSS). An understanding of the role of alloying elements such as silicon (Si) on microstructure details and RSW parameters, both of which influence LME cracking is essential for design of LME-resistant AHSS. The present study has shown that increasing Si-content from 0.7 wt.% to 1.8 wt.% increased LME susceptibility in dual phase (DP) steels. It has been demonstrated that increasing Si led to higher heat inputs and early expulsion due to the higher resistivity of the higher Si-content grade during RSW that was related to more severe LME-cracking. Furthermore, increasing Si-content had a significant effect on microstructural evolution during processing prior to RSW, including increased ferrite grain size, decarburization layer depth, and internal oxides density, all of which were related to an increased LME crack susceptibility.

The Mechanical Properties of Ductile Iron at Intermediate Temperatures: The Effect of Silicon Content and Pearlite Fraction

The use of ductile irons in thermo-mechanically loaded components is increasing, necessitating more knowledge of material properties at intermediate temperatures. A study of the mechanical properties of ductile irons at intermediate temperatures was conducted, investigating the effect of different pearlite fractions along with silicon content tests in fully ferritic microstructures. The effect of the pearlite fraction and silicon content on tensile and yield strength was measured at different temperatures, from room temperature to 450 °C. Models of tensile and yield strengths were developed based on those measurements. These resulting regression models were tested with data from the literature. Such models can be applied in various design tools, such as FEM calculations and in the optimisation of thermally and cyclic loaded ductile iron components.