Influence Of Silicon Addition Research Articles

Morphology evolution and agglomeration mechanism of Fe5Si3 precipitated phase after Fe[sbnd]Si microalloying and its effect on the properties of brasses

The regeneration of scrap brass is affected by the impurity elements in raw materials. It is of practical significance to clarify the interaction of trace elements in brass melt for efficient recovery of scrap brass. The effect of FeSi microalloying on microstructure evolution and properties of as-cast H62 brass was investigated in the present study. The experimental results indicated that the microstructure of H62 brass containing 0.4 wt% Fe changed obviously after the introduction of silicon element. The volume fraction of Fe-rich phase increased with the increase of Si content, and the introduction of Si intensified the agglomeration behavior of Fe-rich phase. The thermodynamic analysis indicated that the silicon showed strong reactivity and bonding ability, and theoretical calculation suggested that silicon preferentially bonded with iron in melt to form new atomic clusters. The introduction of silicon also changed the morphology of the precipitated phase. The influence of silicon addition on the morphology evolution of FeSi precipitated phase was studied. The above reasons should be responsible for the microstructure evolution of as-cast brass. In addition, the mechanical properties and electrical conductivity of the microalloyed brass were tested. This study provides a new insight into the regulation of microalloying elements in regenerated brass.

Influence of Silicon Addition on the Microstructure and Mechanical Properties of WE43 Alloy

Influence of Silicon Addition on the Microstructure and Mechanical Properties of WE43 Alloy

Influence of Silicon Addition on Mechanical Properties and Wear Behaviour of AZ91D Magnesium Alloy Using Stir Casting Method

Influence of Silicon Addition on Mechanical Properties and Wear Behaviour of AZ91D Magnesium Alloy Using Stir Casting Method

Influence of silicon addition on intercritical annealing process and tensile properties of medium Mn steel

This paper presents research on the equilibrium phase fractions, microstructure, and tensile properties of a 0.2C–5Mn–1.5Al (mass %) steel with 0 or 0.5 (mass %) Si addition after intercritical annealing (IA), using thermodynamic simulation, scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, and uniaxial tensile testing. The research results show that the addition of 0.5 Si (mass %) has no significant effect on the equilibrium phase fraction but influences the optimal IA temperature. Different IA temperatures result in the retained austenite having different morphologies. The retained austenite in the 730 °C sample (0.5 Si) has two different morphologies—polygonal and lath—while the 760 °C sample (0 Si) has only polygonal retained austenite. The optimal tensile properties of the 0.5 Si steel are better than those of the 0 Si steel due to the solution strengthening effect of Si and the higher stability of retained austenite. The tensile properties of the investigated 0.5 Si steel are excellent, with a tensile strength of over 1 GPa, elongation over 42.00%, and strength × ductility over 42 GPa%.

The influence of silicon addition in modulation of HA/TCP ratio in biphasic calcium phosphate

Abstract Biphasic calcium phosphate (BCP) granules were prepared using calcium hydroxide (Ca(OH)2) and orthophosphoric acid (H3PO4) as chemical precursors at Ca/P ratio 1.60 via wet chemical technique. Apart from that, silica (SiO2) was also added in the calcium phosphate material as it enhance surface chemical structure, mechanical structure and bioactivity. In this study, 3 wt% silica was added during synthesis to form slurry, before proceeding with spray drying. Granules obtained after the spray drying were calcined at different temperatures (900 – 1300 oC) to study on modulation of HA and TCP phase in BCP. Studies were also conducted on samples’ morphology resulted from spray drying and calcination process. Bioactivity study was also conducted in simulated body fluid (SBF) as a preliminary observation of sample behaviour in-vivo. Addition of silica was found to favour TCP formation and also resulted in faster dissolution process in-vitro.

The influence of silicon additions on the deformation behavior of austenite-ferrite duplex medium manganese steels

The present study systematically investigated the effect of Si additions from 0 to 3 wt.% on the deformation mechanisms of a 0.2C-10Mn-3Al medium Mn steel. Two austenite-ferrite duplex microstructures, characterized by the different austenite characteristics (i.e. fraction and stability), were produced for different Si-alloyed steels by intercritical annealing and subsequently subjected to tensile testing. The influence of Si content on the activation and kinetics of transformation-induced plasticity (TRIP) effect, the formation of deformation twins, as well as the strain partitioning between phase constituents during deformation was studied in detail. For the low austenite fraction (∼30%) duplex structure with a high austenite stability (low Ms temperature), the tensile strength was only slightly changed with Si levels, whereas the uniform elongation was significantly influenced, with first an increase followed by a decreasing trend with higher Si contents. This was attributed to changes in strain partitioning between austenite and ferrite and to different extent of deformation twinning in austenite, which were highly dependent on the solute Si contents and the related microstructural changes. It was found that strain partitioning in this type of microstructure can result in a substantially high strain hardening rate and high uniform elongation. Conversely, for the samples with a high austenite fraction (∼45%) and low stability, the tensile properties were insensitive to the Si content, being mainly controlled by the TRIP effect. In this structure, a higher fraction of martensite was formed at the beginning of the plastic deformation, which decreased the strain partitioning between austenite and ferrite. The TRIP effect after the Lüders strain is believed to be the main factor influencing the strain hardening rate of this type of structure.

Corrosion Behavior of Aluminium Bronze with Addition of Silicon Prepared By Powder Metallurgy

Aluminium bronze (Cu-Al) is widely used in marine application due to its outstanding resistance to corrosion. The addition of alloying elements increases mechanical strength by the formation of heterogeneous microstructures; however this leads to corrosion attack. In order to understand the corrosion behaviour of aluminium bronze alloy, an appreciation of the microstructure is important. There is a gap in the literature regarding the influence of silicon addition on aluminium bronze particularly in corrosion context. In this work, we prepared the aluminium bronze alloys with silicon addition ranges from 0 to 5.0 wt.% by powder metallurgy technique and extensively investigated their corrosion behavior and microstructures. To characterize the corrosion response, electrochemical tests were carried out in sodium chloride solution, supplemented by constant immersion tests and microstructural characterization by means of scanning electron microscopy (SEM). Optical profilometery was used to determine the form and intensity of localized corrosion. The results provide a correlation between chemistry, microstructure and corrosion of silicon containing aluminium bronze.

Influence of silicon addition on the mechanical properties and corrosion resistance of low-alloy steel

The addition of silicon to low-alloy steel allows to modify the materials’ microstructure and thus to improve their corrosion resistance and mechanical properties. The influence of adding different amounts of silicon on the properties (density, transverse rupture strength, microhardness and corrosion resistance) and microstructure of low-alloy steel was investigated. Samples were prepared via the mechanical alloying process, which is the most useful method to homogeneously introduce silicon to low-alloy steel. Sintering was performed by using the spark plasma sintering (SPS) technique. After the SPS process, half of each of the obtained samples was heat-treated in a vacuum furnace. The results show that high-density materials were achieved, and a homogeneous and fine microstructure was obtained. The investigated compositions containing 1 wt% of silicon had better corrosion resistance than samples with 3 wt% of silicon addition. Furthermore, corrosion resistance as well as the mechanical and plastic properties of the samples with 1 wt% of silicon can be further improved by applying heat treatment.

Effect of Silicon Addition on the Properties and Microstructure of Corundum-Mullite Refractory

The influence of silicon addition on the microstructure and properties of corundum-mullite refractory was studied. Results show that Si addition as raw material of the matrix can accelerate mullite crystal formation. The oxidation of Si leads to nucleation of mullite via liquid phase and gas phase. The network microstructure is formed by tiny mullite crystals with few glass phase. So it enhances obviously the high temperature strength of sintered corundum-mullite refractory.

Influence of Silicon Additions on the Microstructure and Mechanical Properties of Cu<SUB>47</SUB>Ti<SUB>34</SUB>Zr<SUB>11</SUB>Ni<SUB>8</SUB> Bulk Metallic Glass Forming Alloys

A group of (Cu47Ti34Zr11Ni8)100−xSix(x=0,1,2,3) bulk metallic glass forming alloys with diameter of 3 mm were prepared by water-cooled copper mould cast. Microstructural investigations reveal that with increasing Si content the precipitated phases exhibit quite different morphologies, which varies from earthworm-like phase for alloys with x=1 to small-sized dendrite phase for alloys with x=2, and finally to developed dendritic phase for alloys with x=3. Room temperature compression tests reveal that a transformation from shear fracture to distensile fracture mechanism occurs for the samples with Si content over a critical value. For the alloys with x=0 and 1, fracture occurs in a shear mode with very high ultimate fracture strength. In contrast, the alloys with x=2 and 3 seem to fracture by a distensile mode with ultimate fracture strength greatly decreased. The fracture behavior of the as-cast alloys were investigated and discussed.

Influence of silicon addition on the oxidation resistance of CrN coatings

Thin CrN and CrSiN films were deposited on steel substrates by DC reactive magnetron sputtering. In this paper, the structure and the oxidation resistance of CrN and CrSiN coatings were studied. Whatever the silicon content, CrN was the sole phase evidenced by X-ray diffraction. Silicon introduction into CrN-based coatings did not modify their preferred orientation. On the other hand, a strong effect of the silicon addition on the film oxidation resistance was noticed. Even for silicon concentration as low as 3 at.%, the films thermal stability, the formation of Cr2N phase and the carbon accumulation at the film-substrate interface were strongly limited. Finally, this value of silicon concentration was sufficient to increase the film oxidation resistance by nearly 150 °C.

Effect of silicon addition on the microstructure and corrosion behavior of sintered stainless steel

The influence of silicon addition on the physical properties and the corrosion behavior of sintered austenitic 304L stainless steel was evaluated. The density of the sintered stainless steel changed depending upon the amount of silicon added. A “pseudo-peritectic” reaction developed during the sintering of high silicon content alloys and resulted in an increased sintering rate and enhanced densification. The corrosion resistance of the various sintered stainless steels was evaluated from the results of potentiodynamic polarization curves and corrosion rate measurements and from the appearance of the corroded surfaces. The results indicated that the corrosion resistance was improved with the addition of more than 2 wt.% Si.

The Influence of Silicon on the Stress Corrosion Cracking Resistance of 18Cr-8Ni-Base Stainless Steels

Abstract As part of a program to develop a stainless steel (SS) resistant to pitting, intergranular corrosion (IGC), and general corrosion while improving the stress corrosion cracking (SCC) resistance, the influence of silicon additions to an 18Cr-8Ni stainless alloy was investigated. Preliminary corrosion data indicated that an 18Cr-8Ni-5Si composition had not only exceptional resistance to IGC following sensitizing heat treatment but also improved general and pitting corrosion resistance. This paper describes the results of further studies aimed at comparing the SCC resistance of the silicon duplex alloys with that of AISI 304 SSs. In addition, preliminary data were obtained on the weldability and formability of silicon-containing duplex stainless alloys. An experimental alloy (18Cr-8Ni-5Si) was found to be immune to SCC in boiling magnesium chloride solution in the annealed condition. The experimental alloy was also markedly superior to AISI 304 SS when tested in the cold-worked condition. The mechani...

Influence of Silicon Addition on the Recrystallization Texture of Al-Fe Alloy

Influence of Silicon Addition on the Recrystallization Texture of Al-Fe Alloy

Influence of silicon additions on the oxidation resistance of a stainless steel

Oxidation tests in a CO2-based atmosphere at 1123 K have been conducted on a series of 20Cr-25Ni stainless steels containing a dispersion of TiN particles and with silicon contents ranging from 0.05 to 2.35 wt.%. In all cases, a chromia surface film whose thickness increased parabolically with time was formed. The parabolic rate constant was a minimum at an intermediate alloy silicon content when an interlayer of silica was formed between the outer oxide and the metal. The significance of this duplex structure on the processes determining the oxidation rate and the extent of oxide spalling is discussed. An additional feature of the attack was the formation of subsurface voidage whose depth again increased parabolically with time. The appropriate rate constant also showed a minimum at an intermediate silicon level and the relationships between this form of attack and the development of the surface oxides are highlighted.

The influence of silicon additions on friction and wear of nickel alloys at temperatures to 1000°F : Donald H. Buckley and Robert L. Johnson. ASLE Trans., 3 (1) (1960) 93–100; 12 figs., 1 table, 11 refs

The influence of silicon additions on friction and wear of nickel alloys at temperatures to 1000°F : Donald H. Buckley and Robert L. Johnson. ASLE Trans., 3 (1) (1960) 93–100; 12 figs., 1 table, 11 refs

The Influence of Silicon Additions on Friction and Wear of Nickel Alloys at Temperatures to 1000 F

Small additions of silicon have considerable beneficial effect on performance on slider alloys. This effect has most frequently been attributed to increased hardness. The research reported was conducted to consider a hypothesis that the primary role of silicon in slider alloys is one of supporting the formation of protective surface films. Friction and wear data were obtained at temperatures from 75 to 1000 F with a series of binary silicon-nickel alloys containing up to 10% silicon. Pertinent hot hardness, metallurgical and surface-film analysis data are included. Atmospheres used were air, mixtures of oxygen and argon, a mixture of hydrogen and nitrogen, and a halogenated methane gas lubricant. The results show the role of silicon as a film former to be of great importance in success of silicon-containing alloys as slider materials for extreme temperatures. The range of variables studied gave friction coefficients from 0.05 to > 10.00 depending on film formation tendencies. Alloys with 5% or more silico...