Influence Of Si Content Research Articles

Influence of Si Content on the Microstructure, Wear Resistance, and Corrosion Resistance of FeCoNiCrAl0.7Cu0.3Six High Entropy Alloy

This study explores microstructure, wear, and corrosion resistance properties of FeCoNiCrAl0.7Cu0.3Six (x = 0, 0.2, 0.3, 0.5) high-entropy alloys. The FeCoNiCrAl0.7Cu0.3Six alloy contains FCC and BCC structures; as the x increases, the FeCoNiCrAl0.7Cu0.3Si0.2, FeCoNiCrAl0.7Cu0.3Si0.4, and FeCoNiCrAl0.7Cu0.3Si0.5 high-entropy alloys transition to BCC structures. The morphological transition in FeCoNiCrAl0.7Cu0.3Six evolves from bamboo leaf-like intergranular features to a discontinuous intergranular structure as Si content increases. The hardness of these alloys gradually increases with higher Si content. The addition of Si promotes a uniform distribution of Cr within and between grains, reducing the intergranular segregation of Cu. Al and Ni show a consistent pattern of elemental distribution throughout the alloy. Wear measurements of FeCoNiCrAl0.7Cu0.3Six alloys demonstrate that adding Si enhances wear resistance, resulting in smoother wear surfaces with reduced deformation. The wear mechanism for all alloys is primarily abrasive, with no brittle fractures observed. Corrosion resistance is optimized when Si content is 0.2, with pitting corrosion being the primary corrosion form.

Influence of Si on the Elevated-Temperature Mechanical and Creep Properties of Al–Cu 224 Cast Alloys during Thermal Exposure

The influence of Si content (0.1–0.8 wt.%) on the development of precipitation microstructures and the resultant mechanical and creep properties during thermal exposure, up to 1000 h at 300 °C, in Al–Cu 224 cast alloys, was systematically investigated. The room and elevated temperature yield strength (YS) increased with increasing Si content under the T7 condition, which was attributed to the fact that the Si promoted the precipitation of fine θ′. However, Si increased the coarsening of θ′ during thermal exposure at 300 °C, and the alloys with low Si exhibited a higher YS and creep resistance at elevated temperatures than high Si alloys. The mechanical strength and creep resistance were mainly controlled by the precipitation strengthening of the predominant θ′ phase. Because of the high mechanical strength and creep resistance of the 0.1Si alloy during long-term thermal exposure, the Si level in Al–Cu alloys should be maintained at a low level of 0.1 wt.% for high-temperature applications. The strengthening mechanisms were quantitatively analyzed, based on the characteristics of the precipitate. The predicted YS values under different exposure conditions agreed well with the experimentally measured values.

Extremely enhanced friction and wear performance of hydrogen-free DLC film at elevated temperatures via Si doping

Hydrogen-free diamond-like carbon (DLC) films have garnered significant attention as a highly efficient solid lubrication material, but poor high-temperature lubrication and wear resistance limit their further application. Here, silicon-doped DLC (Si-DLC) films with different Si contents were deposited using a superimposed HiPIMS-DCMS deposition system to improve their high-temperature lubrication and wear resistance performance. The influence of Si content on the microstructure, mechanical and high-temperature friction and wear behavior of Si-DLC films was investigated. The results showed that Si-DLC films had a dense structure and nanoscale smooth surface. The Si doping enhanced the adhesion strength and relieved the residual stress of Si-DLC films, but decreased the hardness and Young's modulus. Meanwhile, Raman and XPS spectroscopy revealed significant local structural changes in Si-doped DLC films. Furthermore, the results showed that DLC films doped with low Si content displayed excellent tribological performance at elevated temperatures due to the graphite lubricating layer on the surface of wear marks. Specifically, Si-DLC film with 3.31 at% Si had an ultra-low average friction coefficient of 0.04 at 450 °C and still provided effective lubrication at temperatures up to 500 °C. In contrast, pure DLC film failed to lubricate at 450 °C due to the severe graphitization transition and Si-DLC film with 17.47 at% Si quickly failed to lubricate at 200 °C due to the SiC and SiO2. This work sheds light for the high-temperature application of DLC films doped with low Si content by superimposed HiPIMS-DCMS deposition system.

The influence of Si content on precipitation behavior and high-temperature mechanical stability in ERNiMo-2 deposited metal

The influence of Si content on precipitation behavior and high-temperature mechanical stability in ERNiMo-2 deposited metal

Preparation of large diameter/thickness ratio glass shells and “In situ” high temperature infrared spectroscopy study

The millimeter-sized glass (SiO2) shells play key roles in inertial confinement fusion (ICF) experiments, especially for the so-called "direct-drive" configuration. The preparation of large diameter/thickness ratio glass shells and the exploration of transformation mechanisms for silicon-doped glow discharge polymer (Si-GDP) to SiO2 still face challenges. Here, we prepared large diameter/thickness ratio glass shells with the diameter of ∼1200 μm and shell thickness of ∼5 μm by increasing the Si contents in Si-GDP precursors. The influence of Si contents in Si-GDP shells on the compositions, morphologies and geometrical properties of glass shells were carefully investigated. The formability and uniformity of micro morphologies of the glass shells will improve with the increase of Si contents in precursors. The chemical composition of the prepared glass shells is SiO2 with some carbides adsorbed on their surfaces and the compositions present negligible relationship with the Si contents. The sphericity, thickness uniformity and surface quality will increase with the increase of Si contents in precursors. Besides, the oxidation mechanisms for Si-GDP to SiO2 were explored by the combination of an in situ high temperature infrared spectroscopy and a simultaneous thermal analyzer.

Influence of Si contents on the microstructure and corrosion resistance of the Zn−Al−Mg−Si alloys

Hot dip galvanized products are widely used in various aspects of production and life due to their excellent corrosion resistance. Some studies have added a fourth trace alloying element to the zinc aluminum magnesium coating to form a quaternary alloy for better performance. This article prepared two different types of Zn−Al−Mg alloy ingots with trace amounts of Si added by induction melting, consisting of Zn1Al1Mg0.01Si and Zn1Al1Mg0.05Si, and solidified them in a heating furnace with argon gas protection atmosphere. The precipitation process of Zn1Al1Mg(0.01,0.05)Si alloy components under non equilibrium and equilibrium solidification conditions was calculated. The initial crystalline phase of the alloy and the initial solidification temperature were predicted through phase diagram calculations. The microstructure and phase types of the alloy were analyzed using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FE-SEM). The electrochemical Tafel curves of Zn1Al1Mg(0.01,0.05)Si with different Si contents showed that the Zn1Al1Mg0.05Si has the highest corrosion potential and Zn1Al1Mg0.01Si has the lowest corrosion current which means the 1Al1Mg0.01Si alloy possesses the highest corrosion resistance. The Nyqust curves and bode curves also showed that the practical impedance of 1Al1Mg0.01Si alloy is higher than that of 1Al1Mg0.05Si. Moreover, electron probe X-ray micro-analyzer(EPMA) reveals the distribution of Si elements in the Zn1Al1Mg(0.01,0.05)Si. At present, there is little research on the microstructure and properties of quaternary alloys containing silicon. Therefore, studying the influence of silicon content on the microstructure and properties of alloys is of great significance.

Influence of Si content on thermoelectric properties of Mg2(Sn,Si) films by sputtering

Mg2(Sn,Si) films with different Si content were prepared by magnetron sputtering. The phase composition, surface and cross-sectional morphology, chemical composition and element distribution, carrier concentration, carrier mobility, electrical conductivity, Seebeck coefficient and power factor of the deposited Mg–Sn–Si films were studied. The results show that the deposited films are composed of Mg2(Sn,Si) solid solution phase and a small amount of metal Mg phase. The room temperature carrier concentration decreases and mobility increases with increasing Si content in deposited Mg–Sn–Si films, respectively. The room temperature electrical conductivity and Seebeck coefficient decreases and increases with increasing Si content, respectively. The deposited Mg2(Sn,Si) films with moderate Si content possess the maximum power factor value of 2.76 mW m−1 K−2 at 303 °C and its room temperature figure of merit reaches the highest value of 0.44. The thermal conductivity decreases with increasing Si content, indicating that the lattice distortion caused by Si doping can reduce the thermal conductivity of the deposited films.

Influence of Si content on selective oxidation and oxide scale phase transition during hot-rolled coiling

The internal oxidation formed during the advanced high-strength steels hot-rolled coiling process can be inherited into the cold-rolled sheet and impact the final product quality. Herein, the influence of Si on the internal oxidation and oxide scale phase transition behavior of Fe–Mn–Si advanced high-strength steel after hot-rolled coiling are investigated. The results indicate that the internal oxidation depth increases with the increase of Si content and is accompanied by severe intragranular oxidation. Moreover, the interface between Mn–Si oxide and substrate provides a direct diffusion path, which accelerates the rate of internal oxidation. In addition, the displacement reaction of Si/Mn is the primary cause for the formation of continuous pure Fe at the interface of oxide scale/substrate.

Effect of Si content on the surface high-temperature oxidation mechanism in Ni5Y-containing NiAIYSi alloys

The influence of Si content on the oxidation behavior of the Y-related structure (Ni5Y) in NiAlYSi alloy was investigated. The higher Si content increases the diffusion energy barrier of Ni in the Ni5Y phase, preventing the growth of NiO in the outer layer. The inward diffusion of O is effectively impeded by the Y2SiO5+Y2Si2O7+Al2O3+Y2O3 layer produced by the (Ni, Al, Si)5Y phase. The outward diffusion of Ni is also inhibited by this layer. Therefore, the oxidation mechanism of the Ni5Y phase is altered by Si, which has not been found before.

Comparative study on microstructure and properties of nanocrystal and amorphous W–Si–B coatings

Crystalline and amorphous W–Si–B coatings with different Si contents were fabricated by magnetron sputtering. The influence of Si content on microstructure, mechanical and tribological properties of the coatings was evaluated. The results reveals that the crystalline W–Si–B coatings are nanocomposite structures consisting of nanocrystalline AlB2-type WB2 grains and amorphous Si/Si3N4. Crystalline coatings with Si content of 4.7 at.% exhibits the maximum hardness of 35.8 GPa and better fracture toughness compared with pure WB2 coating, leading to the lowest wear rate of 1.3 × 10−7 mm3/Nm. As for the amorphous W–Si–B coatings, the lower hardness of the coatings tends to lead to excellent fracture toughness, which gives rise to the low wear rate. The different enhancement mechanisms of both types of coatings are discussed in detail.

Influence of Si Content on the Microstructure and Tensile Properties of Weathering Bridge Steel Produced via Thermal Mechanical Control Process

In this study, the effects of Si on the microstructure and tensile properties of weathering bridge steel were elucidated. The thermal mechanical control process (TMCP), containing two stages of controlled rolling and accelerated cooling process, was simulated using a thermo-mechanical simulator for four experimental steels with varying Si contents (0.15–0.77 wt.%). Micro-tensile tests were performed, and the microstructures were observed via optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), and electron back-scattered diffraction (EBSD). Furthermore, the tensile properties and microstructures of these steels were analyzed. The results show that a mixed microstructure comprising granular bainitic ferrite (GBF), quasi-polygonal ferrite (QF), and martensite/austenite (M/A) constituent was formed in each sample. With an increase in Si content, the GBF content decreased, QF content increased, mean equivalent diameter (MED) of the QF+GBF matrix increased, and the fraction and average size of the M/A constituent increased. With a rise in Si content from 0.15 to 0.77 wt.%, the contributions of dislocation strengthening, grain boundary strengthening, and precipitation strengthening decreased from 149, 220, and 21 MPa to 126, 179, and 19 MPa, respectively. However, the combined contribution of solution strengthening, lattice strengthening, and M/A strengthening increased from 41 to 175 MPa, which augmented the final yield strength from 431 to 499 MPa. The decreasing yield ratio shows that strain hardening capacity is enhanced due to an increase in the fraction of the M/A constituent as well as in the MED of the QF+GBF matrix. Furthermore, the mechanisms by which Si content controls the microstructure and mechanical properties of weathering bridge steel were also discussed.

Influence of Si content on interface reaction of iron-based hot-dip aluminizing on Fe sheet

Influence of Si content on interface reaction of iron-based hot-dip aluminizing on Fe sheet

Influence of Si content on the machinability of ductile iron

Influence of Si content on the machinability of ductile iron

Influence of Si content on phase stability and mechanical properties of TiAlSiN films grown by AlSi-HiPIMS/Ti-DCMS co-sputtering

Ti 1−x (Al y Si 1−y ) x N coatings covering a wide compositional range, 0.38 < x < 0.76 and 0.68 ≤ y ≤ 1.00, are deposited to investigate the influence of Al + /Si + ion irradiation on microstructural and mechanical properties. The samples are grown in Ar/N 2 atmosphere by the hybrid high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) method with substrate bias synchronized to the Al + /Si + -rich portion of the HiPIMS pulses. Two Ti targets are operated in DCMS mode, while one AlSi target is operated in HiPIMS mode. Four different AlSi target compositions are used: Al 1.0 Si 0.0 , Al 0.9 Si 0.1 , Al 0.8 Si 0.2 , and Al 0.6 Si 0.4 . X-ray diffractometry reveals that films without Si (i.e., y = 1.0) have high Al solubility in NaCl-structure, c-TiAlN, up to x ≤ 0.67 no w-AlN is detected. Once Si (y < 1.0) is introduced the Al solubility limit decreases, but remains higher than other PVD techniques, along with grain refinement and the formation of a SiN z rich tissues phase, as shown by transmission electron microscopy. The nanoindentation hardness is high (~30 GPa) for all films that do not contain the w-AlN phase. All the coatings have compressive stresses lower than −3 GPa. Interestingly, a range of films with different compositions displayed both high hardness (~30 GPa) and low residual stress ( σ < 0.5 GPa). Such a unique combination of properties highlights the benefits of using HiPIMS/DCMS configuration with metal-ion-synchronized substrate bias, which utilizes the Al + /Si + supplantation effect and minimizes the Ar + incorporation. • TiAlSiN films are grown by AlSi-HiPIMS/Ti-DCMS with wide compositional range. • Substrate bias is synchronized to the Al + /Si + -rich portion of the HiPIMS pulses. • The Al + /Si + irradiation effects on film properties are studied. • High Al and Si solubilities in c-TiAl(Si)N are achieved without w-AlN formation. • Specific films yield the combination of low residual stress and high hardness.

Investigation on the corrosion behavior of Ni-Cr-Mo-W-xSi laser cladding coating in H2S corrosion environment

Ni-Cr-Mo-W-xSi laser cladding coating with Si mass fraction changing from 0, 1 wt .%, 3 wt .% to 5 wt .% were fabricated by laser cladding technology. The influence of Si content on the phase constitution, microstructure evolution and high temperature sulfur corrosion resistance were investigated. Experimental results showed that the order of corrosion resistance under H2S corrosion environment at 500-600℃ was S1 > S0 > S3 > S5. The optimized content of Si addition for Ni-Cr-Mo-W-xSi laser cladding coating is 1 wt% due to the benefit of enrichment of Mo and Cr in the inner layer resulting in a protective oxides scale and better corrosion resistance while excessive Si (1% < Si ≤ 5%) caused obvious cracks along the network grain boundaries leading to poor corrosion resistance. Corrosion products such as NiS, Cr2S3, MoO2 and other mixed corrosion products were detected and the multi-layer structure of corrosion scales were observed. The formation of outermost sulfide layer and innermost oxide layer was duo to the corrosion of Ni and Mo leading to a selective formation of Ni-S and Mo-O, respectively. The detailed corrosion mechanisms based on the Gibbs free energy principle were discussed in this study.

Influence of Si content on the microstructure and mechanical properties of silicon stainless steel

The influence of Si addition on the microstructure and mechanical behavior of cast silicon stainless steel alloys was investigated. It was recognized that after incorporation of Si in the range of ∼ 2–6 wt%, microstructure changes significantly. It transforms from single-phase austenitic to duplex microstructure containing ferrite and austenite. In addition, TiC precipitates with angular and spherical morphology were observed in all the sample conditions. Uniaxial tensile tests suggested that the incorporation of Si improved the strength and ductility as long as the microstructure remains primarily austenitic. However, at much higher silicon content (∼6 wt%), microstructure transformed to duplex structure, followed by the drastic reduction in ductility and toughness. Overall, the alloy with ∼4 wt% Si exhibited comparatively better strength, ductility as well as toughness. The mechanical properties of the individual phases, characterized using nanoindentation, indicated that the hardness and modulus of the austenite phase improved significantly after Si incorporation up to ∼6 wt%. Concomitantly correlation between the mechanical properties and crystallographic orientation of grains was also established by performing post-nanoindentation EBSD analysis. The results indicated that the average hardness and modulus of each phase are significantly related to the crystallographic orientation of grains, i.e., it is highly anisotropic. Finally, the nanomechanical properties of the individual phases were utilized to predict and compare the bulk mechanical properties using the ECM model. A reliable quantitative comparison between nanomechanical and bulk mechanical properties of alloys with single-phase microstructure was obtained, whereas a more refined ECMs are required for envisaging the bulk characteristics of the materials with duplex microstructure.

Influences of Si content on the high-temperature oxidation behavior of X10CrAlSi18 ferritic heat-resistant stainless steel at 700 °C and 800 °C

X10CrAlSi18 FHSS (ferritic heat-resistant stainless steel) has received a lot of attention due to its advantageous combination of creep resistance and oxidation resistance. The influence of Si content on the high-temperature oxidation resistance of X10CrAlSi18 FHSS after oxidation at 700 and 800 °C for up to 180 h in air was investigated in this study. According to the results, a higher Si content could coarsen the grain of ferrite and simultaneously increased the amount of (Cr, Fe)23C6 carbides, which caused cracks and reduced the adhesion between the oxide film and the matrix. After oxidation at 700 °C, the oxide film of 0.77Si FHSS and 1.35Si FHSS were found to be primarily composed of Al2O3, SiO2, Cr2O3, Fe2O3, Mn2O3 and MnCr2O4, with thickness of 5.10 μm and 5.56 μm, respectively. The oxide films formed at 800 °C were primarily composed of Al2O3, SiO2, Cr2O3, FeCr2O4, Mn2O3 and MnCr2O4 with thickness of 5.55 μm and 7.37 μm, respectively. A higher Si content was discovered to increase the amount of MnCr2O4 in the outer layer of the oxide film, which resulted in a looser spinel structure and reduced the oxidation resistance of X10CrAlSi18 FHSS.

Investigation on thermal conductivity and mechanical properties of Si3N4 ceramics via one-step sintering

High thermal conductivity Si3N4 ceramics were fabricated using a one-step method consisting of reaction-bonded Si3N4 (RBSN) and post-sintering. The influence of Si content on nitridation rate, β/(α+β) phase rate, thermal conductivity and mechanical properties was investigated in this work. It is of special interest to note that the thermal conductivity showed a tendency to increase first and then decrease with increasing Si content. This experimental result shows that the optimal thermal conductivity and fracture toughness were obtained to be 66 W (m K)-1 and 12.0 MPa m1/2, respectively. As a comparison, the nitridation rate and β/(α+β) phase rate in a static pressure nitriding system, i.e., 97% (MS10), 97% (MS15), 97% (MS20) and 8.3% (MS10), 8.3% (MS15), 8.9% (MS20), respectively, have obvious advantages over those in a flowing nitriding system, i.e., 91% (MS10), 91% (MS15), 93% (MS20) and 3.1% (MS10), 3.3% (MS15), 3.3% (MS20), respectively. Moreover, high lattice integrity of the β-Si3N4 phase was observed, which can effectively confine O atoms into the β-Si3N4 lattice using MgO as a sintering additive. This result indicates that one-step sintering can provide a new route to prepare Si3N4 ceramics with a good combination of thermal conductivity and mechanical properties.

Si-containing diamond-like carbon coatings to improve the wear resistance of solid ceramic end mills

The study’s purpose is to determine the rational Si content in the DLC-Si external layer of (CrAlSi)N/DLC-Si coatings deposited on α/β-SiAlON + TiN ceramics. The influence of Si content on physical and mechanical properties of coatings such as microhardness, modulus of elasticity, and friction coefficient, and wear resistance of solid ceramic end mills in machining nickel alloy NiCr20TiAl is determined.

Effect of Si content on the microstructure and properties of Ti–Si–C composite coatings prepared by reactive plasma spraying

In this study, Ti–Si–C composite coatings were synthesized via plasma spraying of agglomerated powders prepared by a spray drying/precursor pyrolysis technology using Ti, Si, and sucrose powders. The influence of Si content, ranging from 0 wt% to 24 wt%, on the microstructure, mechanical properties, and oxidation resistance of the composite coatings was investigated. Results show that the phase composition of the Ti–Si–C composite coatings changes with the increasing Si content. The coatings without Si addition consist of TiC and Ti3O; the coatings with 6–18 wt% Si are composed of TiC, Ti5Si3, and Ti3O; the coatings with Si content of 24 wt% form only TiC and Ti5Si3 phases. As the Si content increases, the hardness of the Ti–Si–C composite coatings increases first and then decreases, depending on the intrinsic hardness of the ceramic phases, the brittleness of Ti5Si3, and the defects such as pores and cracks. The Ti–Si–C composite coatings have high wear resistance due to the in-situ synthesized high-hardness TiC and Ti5Si3. Owing to the high brittleness of Ti5Si3, the increasing Si content leads to higher wear volume loss at room temperature, which can be partially improved in high-temperature wear tests. The oxidation resistance of Ti–Si–C composite coatings increases with the increase of Si content, and the higher the oxidation temperature, the more obvious the influence of the Si addition on oxidation resistance.