Development and Characterization of Ceramic Matrix Composite (CMC) from Nigerian Kankara Kaolin and Gray Cast Iron Filling

Cam shafts used in automobiles are produced by cast iron (grey cast iron, nodular cast iron) or steel. In this study, effect of chill formation on the surface of grey and nodular cast irons is investigated on the wear behavior, hardness, impact toughness and microstructure of grey and nodular cast irons. For this purpose, four types cam shaft made of grey cast iron with and without chill on the surfaces and nodular cast iron with and without chill on the surfaces, were casted. Mechanical tests were conducted after the camshafts have been produced by casting method. Surface hardness and wear resistance of grey and nodular cast irons have been improved by chill formation on the surfaces and it is concluded that the amount of wear on the surfaces of grey cast iron with chill and nodular cast iron with chill is almost the same. Maximum hardness value was obtained on the surface of grey cast iron with chill. The impact toughness has been found to decrease by chill formation. Maximum impact toughness value was obtained on nodular cast iron. Microstructures of grey cast iron with and without chill and nodular cast iron with and without chill were examined under optical microscope and worn surfaces of cast irons were examined by scanning electron microscopy (SEM). Wear mechanisms of the four types of cast iron were evaluated by SEM examination. Keywords: Cam shafts, Cast irons, Chill formation, Mechanical properties, Microstructure

Effect of misch metal inoculation on microstructure, mechanical and wear properties of hypoeutectic gray cast irons

Engine castings are made in grey iron which has UTS (ultimate tensile strength)around 250 MPa. Requirement is to make grey cast iron with higher strength without loosing grey cast iron properties namely thermal conductivity and damping capacity. Objective is to develop high grade cast iron by adding alloying elements. Base iron was made in medium frequency induction furnace. Furnace was charged with medium carbon steel and foundry returns as charge materials. Carbon and silicon percentage in base iron was raised by adding petroleum coke and ferro silicon alloys during melting stage. Hot liquid metal was taken into ladle and alloy tin (Sn) addition had been done into the same metal Alloyed liquid metal was poured into a drys and mould in the bar form. Inoculation (ferrosilicon) had been done before pouring into sample mould. Base grey iron was alloyed with tin in the range 0.010–0.100 wt %.Four numbers (nos.) of test bar samples had been made in the different tin percentage range keeping copper constant in the range 0.45–0.5 wt %. Tin(Sn) was added in grey iron to study mechanical and microstructural properties. Tensile, hardness and impact test had been performed for mechanical properties study. Microstructural properties had been studied on optical microscope for the same tin varied samples. UTS was found upto 253–376.11 MPa, hardness upto 173–222.33 BHN and impact strength upto 3.33–4 J.

The hardening characteristics of grey cast iron quenched in some locally available vegetable oils (groundnut, palm kernel, shea butter and Soya bean oils) have been studied using hardness values, tensile properties and impact values as major criteria. On a comparative basis, hardening characteristics of grey cast iron quenched in SAE40 engine oil – a good commercial quenching medium – was also studied for hardening process. Microstructural examination revealed, principally, lower bainite and martensite in all the quenched grey cast iron specimens. The mechanical properties of groundnut oil, shea butter oil, soya bean oil and SAE40 engine oil quenched grey cast irons are found to be superior to that obtained for palm kernel oil quenched cast iron, but their wear resistance as shown by the hardness values are inferior to that of palm kernel oil quenched cast irons. However, the wear resistance of the quenched grey cast iron developed in this group of local vegetable oils was superior to that of SAE40 engine oil. The potentials of these oils as quenching media for grey cast iron hardening process ranked in descending order as soya bean, shea butter, groundnut, and palm kernel, with respect to tensile strength values. In general, excellent hardening properties were obtained with these locally available vegetable oils. Hence, the suitability of these oils as a better quenching media than SAE40 oil in hardening process of grey cast iron has been ascertained. Keywords: Graphite flakes, grey cast iron, hardening, mechanical properties, microstructure, vegetable oils.

ASTM specification A 48 classifies gray irons in terms of tensile strength. The usual microstructure of gray iron is a matrix of pearlite with graphite flakes dispersed throughout. Section sensitivity effects are used in the form of a wedge test in production control to judge the suitability of an iron for pouring a particular casting. Mechanical property values obtained from test bars are sometimes the only available guides to the mechanical properties of the metal in production castings. Gray iron castings are used widely in pressure applications such as cylinder blocks, manifolds, pipe and pipe fittings, compressors, and pumps. Where high impact resistance is needed, gray iron is not recommended. The machinability of most gray cast iron is superior to that of most other cast irons of equivalent hardness, as well as to that of virtually all steel. Gray iron is used widely for machine components that must resist wear.

Grey cast iron representing Fe-C alloy as steel. Grey cast iron graphite in form of flake. Grey cast iron at most used compared to other casting metals, this matter because of amenity process production, can be made mass productions and cost of process which competing, etc. Though offering many advantage, but there are some lacking of that is mechanical properties do not as high as steel. To improve the mechanical properties, in this research the grey cast iron was austempered. This process is conducted by holding the specimens at austenite temperature ( 850oC) during 1 until 2 hour, then quenched in NaNO2 and KNO3 as cooler media. At the quench process conducted by temperature variations to knowing effect of quench temperature at the austempered. Impact, Hardness and metalographi testing have been conducted to evaluate effect of austempering on the mechanical properties and micro structure of austempered materials. By austempered treatment, will improve strength of impact equal to 5.83 % until 45.01 % at non-alloyed grey cast iron, and 15.74 % until 43.47 % at alloyed-0,3 % Cr grey cast iron. Improved of hardness properties also happened equal to 8.57 % until 37.11 % at non-alloyed grey cast iron, and 0.85 % until 38.66 % at alloyed-0,3 % Cr grey cast iron.

Cast iron, especially ductile iron, is being used more and more in most countries of the world due to its excellent mechanical properties, castability, and good price. Cast iron alloys can be given a wide range of properties by changing the alloy composition, inoculation, and treatment, heat treatment, or cooling conditions. On a weight basis, most castings are made in gray cast iron. Some examples of gray and ductile iron products are shown in Fig. 1 [1]. The main factors for the high usage are good casting properties, low price, good cutability, and unique properties like damping and good tribology. Lamellar gray cast iron has very good damping capacity. This property is used in many components where damping of sound and vibration is important. Gray iron, also called lamellar graphite iron, is an iron–carbon–silicon alloy with different alloying elements. To understand the microstructure formations and to model them and other important phenomena, both the solidification and the solid-state transformations must be considered. These phase transformations are, to a large extent, affected by nucleation and growth kinetics which are dependent on, for example, handling of the melt, charge material, melting method, metal treatment, inoculation, pouring method, casting process and mold material, cooling power of the mold, and other factors. Many of these important material and process factors and combinations of them are still not fully understood today. Consequently, it is necessary that a foundry producing cast iron components has very strict process control in order to avoid unpredictable problems in production. When this is the case, it will also be possible to use simulation tools for predicting solidification sequence, microstructures, mechanical properties, as well as formation of defects.

Ductile iron is currently one of the most popular construction materials. Its mechanical properties are close to those of steel. The basic material in the production of ductile iron is gray iron, which can be produced in a cupola or in an electric induction or electric arc furnace. After tapping the gray cast iron from the furnace, the gray cast iron is processing into ductile iron. This process is called modification. Magnesium and its alloys and cerium are most often used as modifiers. In addition to the modification, the cast iron must then be inoculated. This paper deals with the impact of gray cast iron modification on the working environment. The experiments were performed in two foundries, where three modification technologies were used: the pouring method, the Tundisch cover and the Flottret method. The aim of the experiments was to determine how the individual modification methods affect the development of magnesium vapor, the content of carbon monoxide in the working environment and the temperature in the working environment. During the experiments, the CO content and temperature were measured before the modification itself, immediately after the modification and one hour after the modification. The greatest development of CO occurred after the modification. This was most significant in the pouring method. A similar situation occurred in the case of a change in temperature. Within one hour of the start of the modification, both the CO content and the ambient temperature returned to the original level before the modification.

In this study, interfacial characteristics in bimetal composites composed of (i) grey cast iron (GCI) as a brittle matrix and (ii) stainless steel (SAE310) and steel wires (AISI1020) as ductile reinforcements were investigated. Flexural behavior of GCI and bimetal composite beams was examined under three-point bending test. Current results revealed that carbon and alloying elements diffused from the molten iron to the ductile reinforcement across the interface enhancing the metallurgical bond across the interface of produced composite beams. The diffusion of carbon from GCI into SAE310 side resulted in the formation of chromium carbides in that side near the interface. Chromium diffused from SAE310 into GCI led to the formation of M7C3 eutectic carbides in GCI near the interface. As a consequence, the ductile reinforcement may lose some of its ductility and behaves as a brittle material especially at the region near the interface. Microhardness and microstructure variations across the interface are related to the diffusion of carbon and alloying elements. The introducing of steel wires with a lower area ratio (i.e. 2.2%) into the GCI matrix bimetal composite did not reveal any obvious developments in changing failure mode of this material. Inserting SAE310 plates into composite beams resulted in a noticeable improvement in their mechanical properties as compared with GCI beam without reinforcement. Specimens of the bimetal composites with SAE310 plates failed in a ductile mode with slight plastic deformation before failure. This may be due to lower volume fraction of SAE310 plates.

The use of agricultural by-products and waste materials as fillers and additives to produce different mix designs with enhanced properties is one of the ways researchers are shifting focus to seek and develop materials that rely on renewable resources. The present research investigates the influence of Palm Kernel Shell Powder (PKSP) on the mechanical properties of inoculated Gray Cast Iron (GCI). Five specimens consisting of sample C0 (0.3%FeSi, 0%PKSP), Sample C3 (0.3%FeSi, 0.3%PKSP), sample C6 (0.3%FeSi, 0.6%PKSP), sample C9 (0.3%FeSi, 0.9%PKSP), and sample C12 (0.3%FeSi, 1.2%PKSP) were developed using sand mold casting method, the chemical analysis, and their mechanical properties (tensile, hardness, and microstructures) were evaluated. The chemical composition shows that the produced gray cast iron solidified within the hypereutectic cast iron range (Carbon Equivalent, CE > 4.5), while the microstructure reveals through the graphite flakes distribution that the produced gray cast iron consists of type A graphite. The highest tensile strength and hardness values were observed in sample C3 with tensile strength and hardness values of 155.97MPa and 156.74 BHN respectively. From the result obtained, an increase in both tensile and hardness values was observed up to 0.3% PKSP addition, beyond this amount, shows a decrease in both tensile strength and hardness values for the developed gray cast iron samples.

Influence of the initial moisture content on the carbonation degree and performance of fiber-cement composites

This research was conducted to explore the influence of inoculants on the microstructure and mechanical properties of grey cast iron. The study also reviews the literature related to graphite morphology, solidification behaviour, and its impact on mechanical properties. However, inconsistencies in reported work highlight the need for a standardised approach to the inoculation of cast iron. Previous studies reported the successes and limitations of these inoculants on grey cast iron identifying the need to explore alternative inoculants such as FeSi-Zr. This study explores the effect of FeSi75-Zr inoculant on the microstructure, thermal and mechanical properties of grey cast iron. FeSi75-Zr inoculants were added at varying quantities of 0.1%, 0.2%, and 0.4% into grey cast iron materials. Additions of inoculant increased eutectic temperature and promoted the formation of short, sharp graphite flakes within the matrix. Notably, the addition of 0.2% FeSi-Zr inoculant resulted in the most refined microstructure and a hardness value that decreased from 172HV of un- inoculated to 156HV of 0.2% inoculanted. Increasing inoculation content led to an increased ultimate tensile strength (UTS) of 229 MPa.

Studies on mechanical and wear properties of alloyed hypereutectic gray cast irons in the as-cast pearlitic and austempered conditions

Mechanical and microstructural properties of low-carbon steel-plate-reinforced gray cast iron

The brake system of an automobile is composed of disc brake and pad which are co-working components in braking and accelerating. In the braking period, due to friction between the surface of the disc and pad, the thermal heat is generated. It should be avoided to reach elevated temperatures in disc and pad. It is focused on different disc materials that are gray cast iron and carbon ceramics, whereas pad is made up of a composite material. In this study, the CFD model of the brake system is analyzed to get a realistic approach in the amount of transferred heat. The amount of produced heat can be affected by some parameters such as velocity and friction coefficient. The results show that surface temperature for carbon-ceramic disc material can change between 290 and 650 K according to the friction coefficient and velocity in transient mode. Also, if the disc material gray cast iron is selected, it can change between 295 and 500 K. It is claimed that the amount of dissipated heat depends on the different heat transfer coefficient of gray cast iron and carbon ceramics.