Erosion behavior of B4C based ceramic nozzles by abrasive air-jet

TiC and Mo were introduced into B₄C-based ceramic nozzles, which were obtained by hot-press sintering. The effect of TiC content on mechanical properties and erosion behavior of B₄C-based ceramic nozzles were analyzed. XRD analysis showed that chemical reactions took place during the sintering process, which resulted in B₄C/Mo/TiB₂ ceramic nozzle with high density and improved mechanical properties compared with B₄C/Mo ceramic nozzle. The sintering temperature was decreased from 2150 °C for B₄C/Mo ceramic nozzle to 1950 °C for B₄C/Mo/TiB₂ ceramic nozzle. Results of erosion wear tests indicated that the hardness and toughness were the key factors influencing the erosion rate of B₄C/Mo/TiB₂ ceramic nozzle. Analysis of the eroded bore surfaces of B₄C/Mo/TiB₂ ceramic nozzle showed that the entry bore section exhibited a brittle fracture induced material removal process, and the center bore section showed plowing and polishing of material removal. Fracture and plowing of material removal occurred at the exit bore section.     

Solid Particle Erosion of Lantana Camara Fiber-Reinforced Polymer Matrix Composite

The present investigation reports the solid particle erosion behaviour of randomly oriented short Lantana-Camara fiber-reinforced polymer composites (LCRPCs) using silica sand particles (200 ± 50 µm) as an erodent. The erosion rates of these composites have been evaluated at different impingement angles (15°–90°) and impact velocities (48 m/s–109 m/s) with constant feed rate of erodent (1.467 ± 0.02 gm/min). Highest wear rates were investigated at impingement angles 45°. Erosive wear rates were found to have a close relationship with the impingement angle of the erodent and speed. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM). Possible erosion mechanisms were discussed.     

Effect of fiber type on mechanical properties of short carbon fiber reinforced B4C composites

In order to enhance the mechanical properties of B₄C without density increase, the short carbon fibers M40, M55J and T700 reinforced B₄C ceramic composites were fabricated by hot-pressing process. The addition of the carbon fibers accelerates the densification of the B₄C, decreases their densities, and improves their strength and toughness. The enhancement effects of the three kinds of carbon fibers were studied by investigating the density, Vickers hardness and the mechanical properties such as flexural strength, flexural modulus and fracture toughness of the composites. The fiber type has a great influence on the mechanical properties and enhancement of the short carbon fiber reinforced B₄C composites. The flexible carbon fiber with high strength and low modulus such as T700 is appropriate to reinforce the B₄C matrix ceramic composites.     

Role of Process Variables on the Solid Particle Erosion of Polymer Composites: A Critical Review

This paper presents a review of the reported research investigations that are related to the solid particle erosion behavior of polymers and polymeric composites. Attention is paid to the effects of test parameters such as erodent type, size of the erodent, impingement angle, impact velocity and stand of distance. On the erosion wear rate of polymer composites. Various predictions and models proposed by different authors to describe and quantify the erosion rate are discussed and their suitability is checked. Recent findings on the erosion response of multi-component hybrid composites are also presented. Lastly the implementation of the design of experiments and statistical techniques in making a parametric appraisal of the erosion processes of composites is discussed.     

Role of Process Variables on Solid Particle Erosion of Polymer Composites: A Critical Review

This paper presents a review of the reported research works that are related to the solid particle erosion behavior of polymers and polymeric composites. Attention is paid to the effects of test parameters such as erodent type, size of the erodent, impingement angle, impact velocity and stand of distance. on the erosion wear rate of polymer composites. Various predictions and models proposed by different authors to describe and quantify the erosion rate are mentioned and their suitability is checked. Recent findings on the erosion response of multi-component hybrid composites are also presented. Lastly the implementation of design of experiments and statistical techniques in making the parametric appraisal of the erosion process of composites is discussed.     

Enhancement mechanical properties of in-situ preparated B4C-based composites with small amount of (Ti3SiC2+Si)

B₄C-based composites were synthesized by spark plasma sintering using B₄C、Ti₃SiC₂、Si as starting materials. The effects of sintering temperature and second phase content on mechanical performance and microstructure of composites were studied. Full dense B₄C-based composites were obtained at a low sintering temperature of 1800 °C. The B₄C-based composite with 10 wt% (TiB₂+SiC) shows excellent mechanical properties: the Vickers hardness, fracture toughness, and flexural strength are 33 GPa, 8 MPa m^1/2, 569 MPa, respectively. High hardness and flexural strength were attributed to the high relative density and grain refinement, the high fracture toughness was owing to the crack deflection and uniform distribution of the second phase.     

Erosion Behavior of Gelcast Fused Silica Ceramic Composites

In this paper, the characteristics of solid particle erosion on fused silica ceramics are investigated. Gelcasting, a near net shape forming process, is adopted for the fabrication of ceramics. Three types of ceramics with a combination of pure fused silica, fused silica+5 wt% silicon nitride (Si₃N₄)?+?1 wt% boron nitride (BN) and fused silica+5 wt% silicon nitride (Si₃N₄) +1 wt% alumina (Al₂O₃) are prepared at a constant 52 vol% solid loading, 10 wt% monomer content and 10:1 monomer ratio. Different impingement angles (30^o, 45^o, 60^o and 90^o) and three impact velocities (86 m/s, 101 m/s and 148 m/s) were chosen to examine the behavior of erosion on gelcasted ceramics using SiO₂ particles as erodent. The maximum rate of erosion is obtained at normal impingement angle (90^o), which shows the brittle nature of ceramics. The impact velocity and angle of impingement have an appreciable effect on erosion rate. Resistance to erosive wear is found to have improved with the inclusion of reinforcements in the fused silica ceramics. The erosion rates of different ceramics are compared. Ceramic composite with a combination fused silica+5 wt% Si₃N₄+ 1 wt% BN shows the highest resistance to wear. The surface roughness and morphology of the eroded surfaces have also been studied.

     

Evaluation of tribological behavior of B4C–hBN ceramic composites under water-lubricated condition

The aim of this study is to evaluate the influence of hexagonal boron nitride (hBN) addition on the tribological behavior of B₄C-based ceramic composites under distilled water lubrication. Water-lubricated sliding tests of hot-pressed B₄C–hBN ceramic composites with different hBN amounts against pure B₄C ceramic were carried out on a pin-disc type wear apparatus. It was found that the addition of hBN into B₄C ceramic matrix resulted in a severe decrease of the friction coefficient from 0.373 for B₄C/B₄C sliding pair to 0.005 for B₄C–20 wt% hBN/B₄C sliding pair. A B₂O₃ tribochemical film formed on the worn surface of the B₄C–hBN specimen protected both B₄C–hBN and B₄C and facilitated the frictional surfaces to smooth. Therefore, the tribological behaviors of the pairs were significantly improved. The formation process of the film and its antifriction mechanism are discussed.     

Microstructure and Wear Behavior of Single layer (CrN) and Multilayered (SiN/CrN) Coatings on Particulate Filled Aluminum Alloy Composites

This article presents the slurry erosive wear behavior of single and multilayer coatings on granite powder reinforced aluminum alloy composites for hydro-turbine blade material. The composites were fabricated by stir casting technique with different weight fraction (0, 2, 4, 6wt.%) of granite powder in 1050 aluminum alloy. In this study, the slurry jet erosive performance of uncoated, single layer and multilayer coating granite powder filled alloy composites in a slurry jet wear test was conducted for four different operating parameters such as filler content (0-6wt.%), impact velocity (10-25 m/s), impingement angle (30-75 ⁰) and erodent discharge (160-280 gm), respectively. The slurry erosion rate was a maximum at 0wt.% granite powder reinforcement in uncoated, single layer and multilayer coating samples such as: 0.0203 gm/kg, 0.00981 gm/kg and 0.00756 gm/kg, respectively at impact velocity of 25 m/sec. Taguchi’s orthogonal array (L ₁₆) was applied to study the experimental results of the uncoated and coated alloy composites. A correlation was derived from the results of the Taguchi experimental design and a proposed predictive equation for estimation of slurry erosion rate of these composites. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were conducted to analyze the topography of the eroded surface of uncoated and coated granite powder reinforced aluminum alloy composites.     

Solid particle erosion behaviour of high purity alumina ceramics

The solid particle erosion behaviour of a high purity, cold isostatically pressed ceramics, CIP-Al₂O₃, is studied in this paper. The influence of particle properties, such as hardness and shape, on erosion is examined, as well as the effect of varying the impingement angle of the erodent stream on the weight loss of alumina ceramics samples. Therefore, the erosive wear behaviour was studied at five different impact angles (30°, 45°, 60°, 75° and 90°), using SiC and SiO₂ particles as erodents.The material loss during solid particle erosion is measured by changes in surface roughness, surface morphology and mass loss.The surface roughness and topography of the eroded Al₂O₃ ceramics were recorded using a profilometer.Scanning electron microscopy (SEM) was used to examine the features of eroded surfaces and to ascertain erosion mechanisms of the tested alumina samples.The results indicate that hard, angular SiC particles cause more damage than softer, more rounded SiO₂ particles. It was found that maximum erosion by both types of particles occurs at an impact angle of 90°.     

Erosion behavior of SiC–WC composites

Dense silicon carbide (SiC) ceramics were prepared with 0, 10, 30 or 50 wt% WC particles by hot pressing powder mixtures of SiC, WC and oxide additives at 1800 °C for 1 h under a pressure of 40 MPa in an Ar atmosphere. Effects of alumina or SiC erodent particles and the WC content on the erosion performance of sintered SiC–WC composites were assessed. Microstructures of the sintered composites consisted of WC particles distributed in the equi-axed grain structure of SiC. Fracture surfaces showed a mixed mode of fracture, with a large extent of transgranular fracture observed in SiC ceramics prepared with 30 wt% WC. Crack bridging by WC enhanced toughening of the SiC ceramics. A maximum fracture toughness of 6.7 MPa*m^1/2 was observed for the SiC ceramics with 50 wt% WC, whereas a high hardness of 26 GPa was obtained for the SiC ceramics with 30 wt% WC. When eroded at normal incidence, two orders of magnitude less erosion occurred when SiC–WC composites were eroded by alumina particles than that eroded by SiC particles. The erosion rate of the composites increased with increasing angle of SiC particle impingement from 30° to 90°, and decreased with WC reinforcement up to 30 wt%. A minimum erosion wear rate of 6.6 mm³/kg was obtained for SiC–30 wt% WC composites. Effects of mechanical properties and microstructure on erosion of the sintered SiC–WC composites are discussed, and the dominant wear mechanisms are also elucidated.     

Structural and mechanical properties of needle‐punched nonwoven reinforced composites in erosive environment

Polypropylene‐based needle‐punched nonwoven reinforced epoxy composites have been fabricated and were evaluated for their thermomechanical response and dry erosion performance. The erosive wear investigations were carried out using silica sand particles as erodent with varying impact velocity, angles of impingement, fiber content, and stand‐off‐distance as the operating variables. Design of experiments (DoE) approach‐based Taguchi analysis was carried out to establish the interdependence of operating parameters and erosion rate. Impingement angle and impact velocity have been found to be the most significant determinants of erosive wear performance of such nonwoven reinforced composites. The composites were also observed to be appreciably resistant to impact content and indentations in addition to exhibiting the absence of any storage‐modulus decay till 60°C accompanied with a nominal increase in the primary transition temperature as revealed from loss‐tangent peaks. The composite with 30 wt % and 40 wt % of nonwoven materials have shown the highest and lowest erosion rates, respectively. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM) and their possible erosion mechanisms are discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of diopside glass–ceramic matrix composite reinforced with aluminum titanate

Glass–ceramic composites in the SiO₂–CaO–MgO–(Na₂O) system, reinforced with 5, 10 and 20 wt.% aluminum titanate were synthesized by pressureless sintering. Optimum sintering temperatures with maximum relative density were determined for each composition. The composites were fired above the crystallization peak temperature of glass–ceramic. Mechanical properties of glass–ceramic and sintered composites, such as fracture toughness, flexural strength and Vickers microhardness, were investigated. The sintered composites were characterized by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that the composite containing 10 wt.% aluminum titanate has desirable behavior in comparison to the base glass–ceramic and the other compositions. It seems that crack deflection by aluminum titanate particles is the prevalent mechanism for improving mechanical characteristics.     

Mechanical properties and microstructure evolution of pressureless-sintered B4C–SiC ceramic composite with CeO2 additive

Boron carbide ceramic composites (B₄C)-silicon carbide (SiC) with the cerium oxide (CeO₂) additive, which was varied from 0 wt% to 9 wt%, were prepared by pressureless sintering at 2150 °C for 60 min. The effect of CeO₂ additive content on the microstructure and mechanical properties of the B₄C–SiC ceramic composites was investigated in detail. In-situ synthesised cerium hexaboride (CeB₆) was identified in the B₄C–SiC ceramic composites. B-rich transition zones (such as B_38.22C₆, B_51.02C_1.82) were formed between the B₄C and CeB₆ grains, which introduced local lattice distortion to increase the sintering driving force. The thermal conductivity coefficient of CeB₆ was higher than that of B₄C, which benefited the delivery of heat quantity and helped achieve a highly dense and uniform sintered body. When the CeO₂ additive was excessively increased (more than 5 wt%), the CeB₆ grains had a large grain size and exhibited an increase in the amount of generated carbon monoxide (CO) gas, which led to an increase in the porosity of the B₄C–SiC ceramic composites and decrease in the mechanical properties. The optimum values of the relative density, Vickers hardness, flexural strength, and fracture toughness of the B₄C–SiC ceramic composite with 5 wt% CeO₂ additive were 96.42%, 32.21 GPa, 380 MPa, and 4.32 MPa m^1/2, respectively.     

Pressureless sintering of B4C-TiB2 composites with Al additions

The effects of Al addition on pressureless-sintering of B₄C-TiB₂ composites were studied. Different amounts of Al from 0% to 5 wt.% were added to B₄C-TiB₂ mixtures (containing up to 30 wt.% TiB₂) and the samples were pressureless sintered at 2050 °C and 2150 °C under Ar atmosphere. Physical, microstructural and mechanical properties were analysed and correlated with TiB₂ and Al additions and sintering temperature. Addition of Al to B₄C-TiB₂ results in increased shrinkage upon sintering and final relative density and lower porosity, the effect is being more evident when both Al and TiB₂ are present. Fracture strength, elastic modulus and fracture toughness of 450 MPa, 500 GPa and 6.2 MPa.m^1/2, respectively were measured.     

A modeling approach for prediction of erosion behavior of glass fiber–polyester composites

In recent years, a fairly good number of articles dealing in characterization of solid particle erosion of glass fiber reinforced composites are available but exhaustive study on this vital aspect leading to understand erosion phenomenon is hardly found in the literature. Therefore, in the present work, a theoretical model based on principle of conservation of particle kinetic energy is developed to determine wear rate of glass–polyester composites due to multiple impact erosion. Room temperature erosion tests are then carried out to study the effect of various control factors in an interacting environment on the erosion behavior of these composites. For this purpose, design of experiments approach utilizing Taguchi’s orthogonal arrays is adopted to test the specimens on air jet type erosion test configuration. The results indicate that erodent size, fiber loading, impingement angle and impact velocity are the significant factors in the order of their influence on wear rate. Taguchi approach enables to determine optimal parameter settings that lead to minimization of erosion rate. Artificial neural network (ANN) approach is applied to the erosive wear data to reach at acceptable predictive models. Scanning electron microscopy of the eroded surface of the composites is performed for observation of the features such as crack formation, fiber fragmentation and matrix body deformation. Finally, popular evolutionary approach known genetic algorithm (GA) is used to generalize the method of finding out optimal factor settings for minimum wear rate.     

Microorganism adhesion inhibited by silver doped Yttria-stabilized zirconia ceramics

The aim of this study was to incorporate silver nanoparticles into yttria-stabilized zirconia (YSZ) ceramic for eliminating microorganism adhesion on dental restoration graft. Y₂O₃ (3% mol) partially stabilized ZrO₂ powder with particle size around 80 nm was employed to fabricate tetragonal phase dominated YSZ ceramic block. Silver nanoparticles were efficiently loaded at pH 9.5 by NaBH₄ reducing of AgNO₃. The biocompatibility of silver incorporated YSZ was evaluated by MTT assay. Antimicrobial activities were quantitatively determined by optical density measurement and qualitatively analysed by scanning electro microscope. Inductively coupled plasma-mass spectrometry (ICP-MS) revealed that YSZ block containing 0.0047 wt% nanosilver, which is safe to mammalian cell, can inhibit the growth of Escherichia coli, Streptococcus mitis and Candida albicans. The pristine YSZ disc had no effect on bacterial growth. This study suggests that silver nanoparticles incorporated into YSZ blocks possess a broad spectrum antimicrobial effect and may help prevent biofilm formation on their surfaces to improve implant survival rate.     

Synthesis and characterization of B13C2 boron carbide ceramic by pulsed electric current sintering

Approximately 400 nm grain sized boron-carbon ceramic was synthesized by the pulsed electric current sintering (PECS) method using boron and carbon powders. Relative density of up to 95% was achieved at sintering temperature of 1900 °C. This ceramic was composed with B₁₃C₂ as major phase and few B₄C and C, which were characterized by X-ray diffraction (XRD) and Rietveld refinement quantitative analysis and chemical analysis (CA) and electron probe microanalysis (EPMA). The microstructure was also observed via transmission electron microscope (TEM).     

Erosive wear of carbon fabric reinforced polyetherimide composites: Role of amount of fabric and processing technique

Plain weave carbon fabric (CF) reinforced Polyetherimide (PEI) composites, hereafter referred to as CF‐PEI composites, containing 40, 55, 65, 75, and 85 vol% of CF were developed using impregnation technique and compression moulding. An additional CF‐PEI composite containing 52 vol% of CF was also fabricated using film technique and compression moulding. These composites were developed in order to explore the effect of fabric content and processing technique on strength properties and erosive wear performance of PEI. These six composites along with unfilled PEI were evaluated for their physical and mechanical properties. The erosive wear performance of these materials was evaluated using angular silica particles as erodent at an impingement angle of 30°. It was observed that fabric content strongly influenced the strength properties as well as erosion resistance. Strength performance, however, did not linearly increase with increase in fabric content. Lowest (40%) and highest (85%) amount of fabric proved least effective in this regard. Similar observations were observed in the case of wear resistance (W_R). CF in the range of 55–75 vol% proved optimum for strength properties and wear performance barring PEI, which showed highest W_R. Between the two processing techniques, impregnation technique (I) proved far superior to the film technique (F) in both strength and wear performance. A fairly good correlation was observed between erosion resistance and a product of interlaminar shear strength, resilience, and elongation. SEM studies on worn surfaces supported the wear behavior. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

The preparation and properties of SiCw/B4C composites infiltrated with molten silicon

Silicon carbide whisker (SiC_w) toughened B₄C composites have been prepared by pressureless infiltration of B₄C–SiC_w–C preforms with molten silicon under vacuum at 1500 °C. The effect of SiC_w addition on bulk density, hardness, bending strength, fracture toughness and microstructure of SiC_w/B₄C composites is discussed. It is revealed that the addition of SiC_w improves the fracture toughness of B₄C ceramic, but reduces its bending strength at the same time. The maximum fracture toughness for SiC_w/B₄C composite with 24 wt% SiC_w addition is 4.88 MPa m^1/2, which is about 9% higher than that of the one without SiC_w, but at the same time, the bending strength reduces to the minimum value 243 MPa, reduced by 25%. XRD analysis shows that the phase composition of reaction bonded SiC_w/B₄C composites is B₄C, SiC, Si, and B₁₂ (C, Si, B)₃, with no residual C. And the main toughening mechanism of SiC_w is whisker pulling up.