Microstructure and dry sliding wear performance of oxide dispersion strengthened austenitic stainless steel

Abstract: The oxide dispersion strengthening (ODS) material are candidates for structural materials in nuclear reactors due to high density of small oxide particles dispersed in the matrix. In this study, the microstructure and wear performance of ZrO₂ stabilized with Y₂O₃ reinforced AISI 316L austenitic stainless steels was investigated. The ODS-316L steel powders were sintered using spark plasma sintering technique. The surface structure and composition of the sintered samples were examined by field emission scanning electron microscopy (FESEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The experimental results were compared with the untreated 316L material. Tribological tests were performed on a ball-on-disc wear tester under dry condition at different applied loads from 5 to 35 N. The sliding distance was 2 mm for 1000 s. A tungsten carbide (WC) ball was used as a counterface material. Results showed that addition of ZrO₂ significantly improved the microhardness values while the presence of ZrO2 phase in the 316L matrix reduces the friction coefficient and increased resistance to sliding wear

Effect of build direction on the microhardness and dry sliding wear behaviour of laser additive manufactured Ti-6Al-4V

Abstract: This work presents micro structural and tribological behaviour of Ti-6Al-4V fabricated by direct metal laser sintering technique. The laser sintering was carried out at laser power of 170 W in an argon atmosphere. The microstructure, phase composition, micro hardness and wear study were determined. It has been found that specimens built vertically (VB) contained vanadium carbide (VC) and titanium oxide (TiO) phases in the present of α and β phases resulting in higher micro hardness as compared to horizontal build (HB) specimens. Wear volume loss was determined in a dry sliding wear configuration. An increase in applied load from 5 N to 25 N resulted in an increment in wear volume loss. The presence of delamination could be observed on the worn surface of HB specimen

Effect of build direction on the microhardness and dry sliding wear behaviour of laser additive manufactured Ti-6Al-4V

Abstract: This work presents micro structural and tribological behaviour of Ti-6Al-4V fabricated by direct metal laser sintering technique. The laser sintering was carried out at laser power of 170 W in an argon atmosphere. The microstructure, phase composition, micro hardness and wear study were determined. It has been found that specimens built vertically (VB) contained vanadium carbide (VC) and titanium oxide (TiO) phases in the present of α and β phases resulting in higher micro hardness as compared to horizontal build (HB) specimens. Wear volume loss was determined in a dry sliding wear configuration. An increase in applied load from 5 N to 25 N resulted in an increment in wear volume loss. The presence of delamination could be observed on the worn surface of HB specimen

Processing of pure titanium containing titanium-based reinforcing ceramics additives using spark plasma sintering

Abstract: The densification behaviour, microstructural changes and hardness characteristics during spark plasma sintering of CP-Ti reinforced with TiC, TiN, TiCN and TiB2 were investigated. Commercially pure Ti powders were dry mixed with varied amounts (2.5 and 5 wt. %) of the ceramic additives using a T2F Turbula mixer for 5 h and at a speed of 49 rpm. The blended composite powders were then sintered using spark plasma sintering system (model HHPD-25 from FCT Germany) at a heating rate of 100oC min-1, dwell time of 5 min and sintering temperature of 950ºC. The sintering of CP-Ti was used as a base study to select the proper spark plasma sintering temperature for full density. Densification was monitored through analysis of the recorded punch displacement and the measured density of the sintered samples using Archimedes method. High densities ranging from 97.8% for 5% TiB2 addition to 99.6% for 5% TiCN addition were achieved at a relatively low temperature of 950°C..

Tribocorrosion behaviours of AISI 310 and AISI 316 austenitic stainless steels in 3.5% NaCl solution

Abstract: In this paper the tribocorrosion behaviours of AISI 310 and AISI 316 stainless steels have been studied under reciprocating sliding condition in 3.5% NaCl solution, using a pin-on-disk tribometer integrated with a potentiostat for electrochemical control. Different sliding loads were used at a constant rotational speed of 60 rpm. The results show that sliding load has significant effect on the tribocorrosion behaviour of both materials. Corrosion attack was severe at sliding load conditions in both materials suggesting corrosion-induced wear as the dominant of the two synergistic components. However, at low sliding load, anodic dissolution and pit formation in AISI 316 was accelerated by sliding action causing wear-induced corrosion to be dominant

Fabrication characteristics and mechanical behaviour of rice husk ash – Alumina reinforced Al-Mg-Si alloy matrix hybrid composites

AbstractThe fabrication characteristics and mechanical behaviour of Al-Mg-Si alloy matrix composites reinforced with alumina (Al2O3) and rice husk ash (RHA, an agro-waste) was investigated. This was aimed at assessing the viability of developing high performance Al matrix composites at reduced cost. Al2O3 particulates added with 0, 2, 3, and 4 wt% RHA were utilized to prepare 10 wt% of the reinforcing phase with Al-Mg-Si alloy as matrix using two-step stir casting method. Density measurement, estimated percent porosity, tensile testing, micro-hardness measurement, optical microscopy, and SEM examination were used to characterize the composites produced. The results show that the less dense Al-Mg-Si/RHA/Al2O3 hybrid composites have estimated percent porosity levels as low as the single Al2O3 reinforced grade (< 2.3% porosity). The hardness of the hybrid composites decreases slightly with increase in RHA content with a maximum reduction of less than 11% observed for the Al-4 wt% RHA-6wt% Al2O3 composition (in comparison with the Al-10 wt% Al2O3 single reinforced composition). Tensile strength reductions of 8% and 13%, and specific strengths which were 3.56% and 7.7% lower were respectively observed for the 3 wt% and 4 wt% RHA containing hybrid composites. The specific strength, percent elongation and fracture toughness of the 2 wt% RHA containing hybrid composite was however, higher than that of the single Al2O3 reinforced and other hybrid composite compositions worked on. RHA thus has great promise to serve as a complementing reinforcement for the development of low cost-high performance aluminum hybrid composites

Flow-induced corrosion behaviour of low alloy steel in the presence of mono-ethylene glycol

Abstract: The flow-induced corrosion behaviour of welded low ally steel in 1 wt. % NaCl environment containing monoethylene glycol at 0oC and 25 oC respectively, was investigated. A modified submerged impinging jet rig was adopted to simulate the low temperature environment. Varying speeds between 1 and 3 m/s were used to study the degradation mechanism of the welded steel. Also, the ratio of MEG: 1 wt. % NaCl was kept at 1:4 for the MEG/NaCl solution. Static corrosion condition was also studied and compared with the flowing conditions. Results indicated that the alloy degraded with observable weight loss in pure 1wt. % NaCl at both temperatures whereas there was very negligible weight loss in all the samples in MEG/NaCl solution

Influence of SiAlON ceramic reinforcement on Ti6Al4V alloy matrix via spark plasma sintering technique

Abstract : The titanium-based composite was fabricated by strengthening Ti6Al4V alloy with addition of SiAlON ceramics utilizing spark plasma sintering technique. Ti6Al4V and SiAlON powders were mixed in a T2F Turbula mixer with different propor- tions (5, 10, 15 and 20 vol%) and the admixed powders were consolidated using spark plasma sintering to produce titanium matrix composites. The characterization of the sintered composites was performed using X-ray diffraction, optical microscopy and scanning electron microscopy. The influence of SiAlON additions on densification, microstructure, microhardness and fracture morphology were investigated on the sintered composites. The experimental results revealed that the densification of the sintered titanium matrix composites was in the range of 95%–98%, which decreased with an increase in SiAlON addition. However, an increase in microhardness values ranging from 363 to 574 HV0.1 was achieved. The microstructure shows that the SiAlON ceramic particle was uniformly distributed within the titanium matrix composites which comprises of a mixture of lamellar colonies with β grain boundaries. The fracture features of all composites exhibit mixed fracture of both intergranular and transgranular fracture mechanism

Effects of ternary metal additions on corrosion of spark plasma sintered Ni-Fe alloys in H2SO4 and NaCl

Abstract: Effect of ternary additions on electrochemical behavior of Ni-Fe binary alloys developed by Spark Plasma Sintering (SPS) were investigated and reported. All specimens revealed common passivity behavior in H2SO4. Both binary and ternary alloys did not reveal passivity region under saline conditions. The alloys have lower corrosion rates in NaCl than in H2SO4. Binary Ni50Fe50 alloy is characterized by large pits in H2SO4 and homogeneous corrosion on surface in NaCl. Ni50Fe40Ta10 shows better passivity in 1 M H2SO4 and Ni50Fe40Al10 has the lowest corrosion rate in 3.5 wt.% NaCl

Nanoindentation studies and analysis of the mechanical properties of Ti-Nb2O5 based composites

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