Microstructure Characteristics and Possible Phase Evolution of the Coal Gangue-Steel Slag Ceramics Prepared by the Solid-State Reaction Methods

Industrial wastes such as steel slag and coal gangue etc.were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method.With steel slag and coal gangue mixed in various mass ratios,from 100%steel slag to 100%coal gangue at 10%intervals,microstructure and possible phase evolution of the coal gangue-steel slag ceramics were investigated using X-ray powder diffraction,scanning electron microscopy,mercury intrusion porosimetry and Archimedes boiling method.The experimental results suggest that the phase compositions of the as-prepared ceramics could be altered with the increased amount of coal gangue in the ceramics.The anorthite-diopside eutectic can be formed in the ceramics with the mass ratios of steel slag to coal gangue arranged from 8:2 to 2:8,which was responsible for the melting of the steel slag-coal gangue ceramics at relatively high temperature.Further investigations on the microstructure suggested that the addition of the proper amount of steel slag in ceramic compositions was conducive to the pore formation and further contributed to an increment in porosity.

Failure pattern in ceramic metallic target under ballistic impact

The ballistic resistance and failure pattern of a bi-layer alumina 99.5%-aluminium alloy 1100-H12 target against steel 4340 ogival nosed projectile has been explored in the present experimental cum numerical study.In the experimental investigation,damage induced in the ceramic layer has been quantified in terms of number of cracks developed and failure zone dimensions.The resultant damage in the backing layer has been studied with variation in the bulge and perforation hole in the backing layer with the varying incidence velocity.The discussion of the experimental results has been further followed by three dimensional finite element computations using ABAQUS/Explicit finite code to investigate the behaviour of different types of bi-layer targets under multi-hit projectile impact.The JH-2 constitutive model has been used to reproduce the behaviour of alumina 99.5%and JC constitutive model has been used for steel 4340 and aluminium alloy 1100-H12.The total energy dissipation has been noted to be of lesser magnitude in case of sub-sequential impact in comparison to simultaneous impact of two projectiles.The distance between the impact points of two projectiles also effected the ballistic resistance of bi-layer target.The ballistic resistance of single tile ceramic front layer and four tile ceramic of equivalent area found to be dependent upon the boundary conditions provided to the target.

A Ballistic Limit Analytical Model of Tungsten Ball Perforating Ceramic/Aluminum Composite Target

From the experimental data on ceramic/aluminum composite target, the mechanism of tungsten ball impacting a ceramic/aluminum composite target has been studied. By analyzing the transition of energy in the process of impact, a simple ballistic limit analytical model of tungsten ball impacting a ceramic/aluminum composite target has been proposed; and the result taken from this model is consistent with that of the experiment.

Thermodynamic analysis and formula optimization of steel slag-based ceramic materials by FACTsage software

Using steel slag as a main raw material of ceramics is considered as a high value-added way. However, the relationship among the initial composition, ceramic microstructure, and macroscopic properties requires further study. In this paper, a series of ceramics with different slag ratios （0-70wt%） were designed, and the software FACTsage was introduced to simulate the formation of crystalline phases. The simulation results indicate that mullite is generated but drastically reduced at the slag ratios of 0-25wt%, and anorthite is the dominant crystalline phase in the slag content of 25wt%-45wt%. When the slag ratio is above 45wt%, pyroxene is generated more than anorthite. This is because increasing magnesium can promote the formation of pyroxene. Then, the formula with a slag content of 40wt% was selected and optimized. X-ray diffraction results were good consistent with the simulation results. Finally, the water absorption and bending strength of optimized samples were measured.

Complementation in the composition of steel slag and red mud for preparation of novel ceramics

A method for preparing novel ceramics was developed in this study. Different ratios red muds were added to steel slags to optimize the preparation of novel ceramics by a traditional ceramic preparation process. The sintering mechanism, microstructure, and performance were studied by X-ray diffraction techniques, scanning electron microscopy, and combined experiments of linear shrinkage, water absorption, and flexural strength. The results confirmed that red mud can reduce the volumetric instabilities through the complementarity of red mud and ferroalloy slag. The crystal phases in the ceramics are all pyroxene group minerals, including diopside ferrian, augite, and diopside. The flexural strength of the ceramic that contains 40 wt% red mud and was prepared at the optimal sintering temperature(1140°C) is greater than 93 MPa; its corresponding water absorption is less than 0.05%.

Synthesis of steel slag ceramics: chemical composition and crystalline phases of raw materials

Two types of porcelain tiles with steel slag as the main raw material （steel slag ceramics） were synthesized based on the CaO-A1203-SiO2 and CaO--MgO-SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite, a-quartz, magnetite, and pyroxene crystals （augite and diopside） in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction （XRD） and electron probe X-ray microanalysis （EPMA） results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.

Study on the performance of ceramic composite projectile penetrating into ceramic composite target

In order to study the performance of ceramic composite projectile penetrating into ceramic composite target,the contrast test and numerical simulations of the penetration of standard projectile and the ceramic composite projectile into a ceramic composite target were conducted.The results show that the penetration performance of ceramic composite projectile is obvious superior to that of standard projectile for ceramic composite target.The ceramic nose of ceramic composite projectile fully destroys the ceramic panels anterior to its following armor-piercing projectile body,thus maintaining the penetration ability of the following armor-piercing projectile body.

BEHAVIOUR OF BUFFER LAYER IN JOINING OF SIALON CERAMICS TO STEEL 40Cr

The buffer layer material itself may be influential to the bond strength between active brazing filler and ceramics.For Ag_(57)Cu_(38)Ti_5 filler metal,Cu or Ta is excellent buffer layer material, but Kovar or Ni-15Cr-15Co is worse.It was important to design a layer of soft buffer,such as Cu,to relax interfacial stress rather than hard buffer layer,such as Mo,to avoid stress. There is an optimum thickness range of soft buffer layer,saying h/L=0.02—0.1. It was a good solution to the interfacial stress problem to use soft/hard buffer layer to increase metal/ceramics joint strength.Finally,an idea of designing gradual materials as buffer layer between metal and ceramics was suggested.

Experimental and numerical study on the influence of shaped charge liner cavity filing on jet penetration characteristics in steel targets

Penetration characteristic(size and shape of penetration craters made in high hardness ARMSTAL 30PM steel) of shaped charge jets formed after detonations of modified PG-7VM warheads was analyzed in the article. Modifications consisted in removing the frontal part of the grenade(fuse, ballistic cap and conductive cone) and introducing of the liner cavity filling made of polyacetal copolymer POM-C. The filings in the form of solid cones with three different heights(33%, 66% and 100% of H-the height of original PG-7VM liner) were placed inside of the hollow cone shaped charge liner. As opposed to the vast majority of previously published works(in which warhead optimization studies were focused on increasing of the depth of penetration in rolled homogeneous armor steel) the main aim of the presented modifications was to maximize the damage ratio(diameters of craters, inlet and outlet holes) of target perforated by shaped charge jet at the cost of the loss of part of the jet penetration capability. According to the best knowledge of the authors such approach to the use of the old PG-7VM warheads has not been analyzed so far. Taking into consideration high stock levels of PG-7VM warheads, and the fact that they are continuously being replaced by more efficient and more sophisticated high-explosive anti-tank warheads, it seems reasonable to look for alternate applications of the warheads withdrawn from the service. Thanks to the introduction of proposed modifications the warheads could be used by special forces or other assault units as directional mines or statically detonated cutting shaped charges as well as by combat engineers as universal charges used in various types of engineering or sapper works. The research included experimental penetration tests and their numerical reproduction in the LS-Dyna software with the simulation methodology defined and validated in previous works of the authors.Small differences(average error = 10-20%) were identified between the experimental and numerical results(dimensions of craters made in steel targets were compared) what confirmed the reliability of the modelling methodology and enabled its use for further optimization of the shapes of fillings. Within the analyzed variants of warheads modifications maximum diameters of penetration craters were obtained for the filling of the height of h = 2/3H. The diameters of holes in individual steel plates were increased by 164%, 70%, 65%(for the first, second and third plate, respectively) in relation to the variant without filling. The results of the study indicated that with the use of different materials of fillings and their various heights it is possible to control the shape of penetration craters pierced in the steel targets.

FEM simulation on residual stress distribution during diffusion bonding between Ti （ C, N） metallic ceramic/interlayer/40Cr steel

Based on ANSYS FEM software, the distribution of residual stress in the diffusion bonding joints between Ti（ C,N） metallic ceramic/interlayer/4OCr steel was calculated and experimentally ver^ed. The results showed that the trend on the distribution of residual stress field in the joints was not changed with the use of interlayer. The maximum residual stress was always located in metallic ceramic with area ranging from 1 mm to 4 mm to the interlayer. The maximum residual stress in the joints was also affected by diffusion temperature. The satellite pulse current during the initial stage on diffusion bonding can promote the formation of liquid film at the interface, by which diffusion temperature and loading pressure can be greatly decreased. The crack initiation was easily produced at the corner of Ti （ C, N） metallic ceramic close to the interlayer. If a higher residual stress produced in the joints, the crack was propagated into the whole ceramic.

A novel process of preparing glass-ceramics directly from molten steel slag

A novel process technology to prepare glass-ceramics directly from molten steel slag （MSS） is proposed in the study. The liquid-solid mixing method was used to adjust the components of the MSS and glass-ceramics was obtained. The effects of heat-treatment conditions on the microstructure ,physical and mechanical properties of samples were studied. Economical benefits of the novel process were analyzed. The results show that heat-treatment is a very effective approach to achieving crystallization. The dominant crystal phase in products is diopside [ （ Mg6Al2Fe2 ） Ca （ Si1.5 Al5 ） O2 ]. The shape of the crystallization is like a granule. The glass-ceramic samples exhibited good mechanical properties and presented chemical stability. The economic benefits of the process are remarkable due to less energy consumption compared with conventional glass-ceramics production methods.

Corrosion Resistance of Ceramic Coating on Steel Substrate

Fe/Al2O3 ceramic coating was made by spraying and sol-gel. The corrosion resistance between Fe/Al2O3 ceramic coating and steel 45# was studied. By microscope and X-ray diffraction, the binding and the composition of the interface were also analyzed. The results showed that Fe/Al2O3 ceramic coating had dense struc- ture, less porosity and better binding with the substrate which was effective to prevent erosive liquor immersing into the inside of ceramic coating. Some substances that distributed homogeneously in Fe/Al2O3 ceramic coating, such as α-Al2O3, FeAlO3 and Fe3Al, could improve the corrosion resistance of this material.

Processing and mechanical properties of network ceramic/steel composites by pressureless infiltration

A new style Ni-containing alumina ceramic foam based continuous three-dimensional interconnected skeleton was prepared by impregnating a polymeric sponge with aqueous ceramic slurry.Subsequently,alumina ceramic foam/steel metal matrix composites(MMCs) were prepared successfully by sand mold casting technique.The microstructure and mechanical properties of MMCs were investigated by SEM,EDS and compressive test.The results show that the depth of infiltration is about 40 μm to the bonding interface of ceramic/steel and the fracture strength σmax and plastic strain limit εp of composite are 520 MPa and 11.2%,respectively.The fretting wear mechanism of MMCs is mainly performed at the oxidative wear mode with lower load/friction frequency and the predominant oxidation wear together with slight adhesive wear and abrasive wear multiple mode with higher load/ friction frequency.Moreover,the infiltration bonding and continuous three-dimensional interconnected ceramic skeleton play a vital role in the stability of the bonding interface and excellent mechanical properties.

Effect of Metallurgical Behaviour at the Interface between Ceramic and Interlayer on the Si_3N_4/1.25Cr-0.5Mo Steel Joint Strength

By using newly developed CuNi5~25Ti16~28 B rapldly solidifled brazing filler the joining of Si3 N4/1.25Cr-0.5Mo steel has been carried out with interlayer method. If employing the interlayer structure of steel (0.2 mm)/W (2.0 mm)/Ni(0.2 mm), the joint strength can be increased greatly compared with employing that of Ni/W/Ni, and the three point bend strength of the Joint shows the value of 261 MPa. The metallurgical behaviour at the interface between Si3N4 and the interlayer has been studied. It is found that Fe participated in the interfacial reactions between Si3N4 and the brazing filler at the Si3N4/steel (0.2 mm) interface and the compound Fe5Si3 was produced. However, since the reactions of Fe with the active Ti are weaker than those of Ni with Ti, the normal inter facial reactions were still assured at the interface of Si3N4/steel (0.2 mm) instead of Si3N4/Ni (0.2 mm), resulting in the improvement of the joint strength. The mechanism of the formation of Fe5Si3 is also discussed. Finally, some ideas to further ameliorate and simplify the interlayer structure are put forward.

Effect of Ceramic Powder Coatings on Low Carbon Steel

Effect of ceramic powder coating on low carbon steel samples was presented. Electrostatic deposition method was used to produce ceramic coatings on low carbon steels. The coatings were fabricated over a range of temperatures (100℃ - 400℃). Detailed investigation on the corrosion behaviour, the hardness property and electrode potential of the fabricated and uncoated samples are reported. The ceramic materials used are locally available in Ondo-State Nigeria. The coating temperatures affect the rate of corrosion, the hardness property and the electrical resistivity of the coated steel sample. The sample coated at 300℃ with ceramic powder Y showed the best corrosion resistance in 0.5 M NaCl solution. The highest resistivity occurred in the sample coated at 300℃ with ceramic powder Z. All the samples coated with ceramic powder Y had better corrosion resistance in 0.5 M NaCl than the one coated by sample Z.

Experimental study on glass-ceramics preparation from hot steel slag

When liquid steel slag produced from steelmaking process was treated into the post-cold slag by conventional methods,the great deal of slag heat was dissipated into the environment,causing a lot of energy waste and environmental pollution.In this study,a novel approach of direct utilization of hot steel slag as a raw material and slag heat for the production of glass-ceramics was proposed and experimentally tested.In order to simulate liquid slag from steelmaking electric furnace,40%water-quenched slag was remelted at 1 450℃and then mixed with 60%melting additives(silica powder,alumina powder and sodium oxide, etc.)and subsequently melted together at 1 500℃for 1 h into modified liquid slag which was cast,heat-treated, annealed and transformed into glass-ceramics.The heat-treated glass samples were investigated using differential thermal analysis(DTA),X-ray diffraction(XRD),and scanning electron microscopy(SEM). The results show that dominant crystalline phase is diopside[CaFe(SiO_3)_2]and the shape of the crystal is like the granule,diameter is about 0.2 -0.6μm.A glass-ceramic with nucleation temperature of 695℃for two hours and crystallization temperature of 893℃for one hour and 1 163℃for half-hour exhibited the best combination of properties.This method of slag mixed with melting additives to adjust the composition of the parent glass is important for the industrial production of glass-ceramics by direct utilization of hot steel slag.

Purification performance on molten steel of novel Al_(2)O_(3)-based ceramic filter prepared from microporous powder and nano-Al_(2)O_(3) powder

Reticulated ceramic foam filters provide an effective way to purify molten steel by removing non-metallic inclusions.We proposed a novel strategy to improve the purification performance of Al_(2)O_(3)-based ceramic filters by using microporous corundum-spinel raw materials to replace dense raw materials.Three kinds of Al_(2)O_(3)-based ceramic filters fabricated from dense α-Al_(2)O_(3) micro-powder or microporous corundum-spinel powder were selected to carry out the immersion tests with molten steel.On the one hand,the higher surface roughness of the filter skeleton prepared from microporous raw materials increased the adsorption capacity of skeleton surface on inclusions in molten steel.On the other hand,the higher apparent porosity and larger pore size of the filter skeleton were more beneficial to the penetration of molten steel in the micropores of skeleton.The reaction process at the solid-liquid interface also improved the wettability of the interface between skeleton and molten steel,resulting in a larger penetration depth and a better adsorption effect on the inclusions.In summary,the novel Al_(2)O_(3)-based ceramic filter prepared with microporous corundum-spinel powder and addition of 5 wt.% nano-Al_(2)O_(3) powder reduced the total oxygen content of the steel from 40.2×10^(-4) to 12.7×10^(-4) wt.% by 68.4% and the Al content from 0.46 to 0.18 wt.% by 60.9% after immersion test,presenting the most excellent purification performance on molten steel.

A method for preparing composite diffusion coating alloy on ceramic surface

Metallization of the ceramic surfaces of Si3N4 and Al2O3 was carried out in a composite diffusion coating vacuum furnace using a Ti-Cu composite target. The experimental process and influencing factors were discussed. Optical microscope （OM） , energy dispersive spectroscopy （EDS） , scanning electron microscopy （SEM） , X-ray diffusion （XRD） and sound emissive scratch test （SEST） were applied to evaluate the alloy layer formed on the ceramic surface. It was indicated that the diffusion coating alloy layer contained Cu, Ti, Fe, Al and Si etc. XRD result indicated that the diffusion coating alloy layer was composed of CuTi2, Cu, Si2 Ti and CuTi, Al2 TiO5 , Ti3O5. It was found that the diffusion coating alloy layer got bonded with ceramic well, and no spaUation occurred under the maximum load of 100 N. Deposited Si3N4 ceramic was welded with Q235 and the joining quality was examined. Robust joint was formed between Si3N4 ceramic/Q235. This present method has advantages in high efficiency and low cost and provides a new approach for producing ceramic and metal bond.

Selection and modification of ground motion records using Newmark-Hall spectrum as target spectrum for long-period structures

Input ground motions have significant impacts on the uncertainty of structural responses in time-history analysis.In this study,records were selected and scaled for the evaluation of mean structural responses according to the target spectrum.The Newmark-Hall spectrum is closely related to seismic response of short,medium and long-period structures,so it was taken as the target spectrum here.The nonlinear time-history analyses of 9-story and 20-story steel moment-resisting frame structures were carried out as examples.They represent medium and long-period buildings,respectively.Three target spectra with risk of 50%,10%and 2%probabilities for exceedance in 50 years were calculated by the average Newmark-Hall spectrum method for three ground motion sets developed in the SAC Steel Project.The predicted structural mean responses of these Newmark-Hall spectra were compared with those calculated by the average spectral acceleration method for the same record set.It is found that both methods have similar accuracy for estimating the structural mean response.However,the method proposed herein is more effective in reducing the variability of the structural responses.Also,the proposed method is more advantageous for the time-history analysis of long-period structures or structures with more severe nonlinear responses under strong seismic excitations.

Mechanical and Microstructural Analysis of Waste Ceramic Optimal Concrete Reinforced by Hybrid Fibers Materials: A Comprehensive Study

Combining different types of fibers inside a concrete mixture was revealed to improve the strength properties of cementitious matrices by monitoring crack initiation and propagation.The contribution of hybrid fibers needs to be thoroughly investigated,considering various parameters such as fibers type and content.The present study aims to carry out some mechanical and microstructural characteristics of Waste Ceramic Optimal Concrete(WOC)reinforced by hybrid fibers.Reinforcement materials consist of three dif­ferent fiber types:hook-ended steel fiber(HK),crimped steel fiber(CR)and polyvinyl alcohol(PVA)fibers and the effect of their addition on the waste ceramic composites’mechanical behaviour.Furthermore,a micro­structural analysis was carried out to understand the waste ceramic matrix composition and its bonding to hybrid fibers.Results showed that the ad­dition of hybrid fibers improved the strength characteristics of the ceramic waste composites.For instance,the existence of PVA-CR increased the tensile and flexural strength of the waste ceramic composite by 85.44%and 70.37%,respectively,with respect to the control sample(WOC).As well as hybrid fiber exhibits improved morphological properties as a result of in­creased pore filling with dense and compact structure,as well as increased C-H crystals and denser structure in pastes as a result of the incorporation of hybrid fibers into the concrete mix.The present experimental research shows the choice of using steel fiber with PVA as a reinforcement material.The idea of adding hybrid fiber is to prepare the economic,environmental,and technological concrete.Moreover,it offers a possibility for improving concrete’s durability,which is vital.Finally,it was concluded that steel fiber is more durable,and stiffer and provides adequate first crack strength and ultimate strength.In contrast,the PVA fiber is relatively flexible and improves the post-crack zone’s toughness and strain capacity.