8 research outputs found
Cavitation Erosion Tests Performed by Indirect Vibratory Method on Stainless Steel Welded Samples with Hardened Surface
The paper presents the results of cavitation erosion tests performed on
two types of samples. The materials of the samples are frequently used
for manufacturing and repairs of the hydro turbines components submitted
to cavitation. The first sample was made by welding of an austenitic
stainless steel on austenito-feritic base material. The second
sample was made similarly with the first but with a martensitic base
material. After the welding processes, on both samples was applied a
hardening treatment by surface peening. The cavitation erosion tests
were performed on vibratory equipment using the indirect method with
stationary specimen. The results show a good cavitation erosion resistance on both samples
Investigations of Cavitation Erosion and Corrosion Behavior of Flame-Sprayed NiCrBSi/WC-12Co Composite Coatings
Flame-sprayed NiCrBSi/WC-12Co composite coatings were deposited in different ratios on the surface of stainless steel. Oxyacetylene flame remelting treatment was applied to surfaces for refinement of the morphology of the layers and improvement of the coating/substrate adhesion. The performance of the coated specimens to cavitation erosion and electrochemical corrosion was evaluated by an ultrasonic vibratory method and, respectively, by polarization measurements. The microstructure was investigated by means of scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX). The obtained results demonstrated that the addition of 15 wt.% WC-12Co to the self-fluxing alloy improves the resistance to cavitation erosion (the terminal erosion rate (Vs) decreased with 15% related to that of the NiCrBSi coating) without influencing the good corrosion resistance in NaCl solution. However, a further increase in WC-Co content led to a deterioration of these coating properties (the Vs has doubled related to that of the NiCrBSi coating). Moreover, the corrosion behavior of the latter composite coating was negatively influenced, a fact confirmed by increased values for the corrosion current density (icorr). Based on the achieved experimental results, one may summarize that NiCrBSi/WC-Co composite coatings are able to increase the life cycle of expensive, high-performance components exposed to severe cavitation conditions
Contributions in the Preparation and Processing of Composite Material Type Silumin 3 - Reinforced Matrix with S235JR Steel Mesh
In the paper are presented concrete data on developing technological
batches of metal composite material (MCM) type Silumin 3-reinforced
matrix with steel mesh S235JR, with the indicating of the parameter
and of the distinct stages of work. The samples from prepared batches
were cut along and across by water jet abrasive process and were subjected
to a destructive testing program and microstructural examination,
obtaining results in concordance with the desired quality. The
abrasive material used for cut was GMA granite with the average mesh
of 80, the particle size ranging between 150-300 µm, density 2300
kg/m3 and melting point 1240°C
Investigations of Cavitation Erosion and Corrosion Behavior of Flame-Sprayed NiCrBSi/WC-12Co Composite Coatings
Flame-sprayed NiCrBSi/WC-12Co composite coatings were deposited in different ratios on the surface of stainless steel. Oxyacetylene flame remelting treatment was applied to surfaces for refinement of the morphology of the layers and improvement of the coating/substrate adhesion. The performance of the coated specimens to cavitation erosion and electrochemical corrosion was evaluated by an ultrasonic vibratory method and, respectively, by polarization measurements. The microstructure was investigated by means of scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX). The obtained results demonstrated that the addition of 15 wt.% WC-12Co to the self-fluxing alloy improves the resistance to cavitation erosion (the terminal erosion rate (Vs) decreased with 15% related to that of the NiCrBSi coating) without influencing the good corrosion resistance in NaCl solution. However, a further increase in WC-Co content led to a deterioration of these coating properties (the Vs has doubled related to that of the NiCrBSi coating). Moreover, the corrosion behavior of the latter composite coating was negatively influenced, a fact confirmed by increased values for the corrosion current density (icorr). Based on the achieved experimental results, one may summarize that NiCrBSi/WC-Co composite coatings are able to increase the life cycle of expensive, high-performance components exposed to severe cavitation conditions
Influence of the Fusing Process on the Wear and Corrosion Properties of NiCrBSi-Coatings
In this study the NiCrBSi feedstock powder was deposited by flame
spraying on to C45 steel substrate. After spraying the coated material
was differently fused at 1000°C. The microstructure evolution respectively
the phase composition was evaluated by means of scanning electron
microscopy (SEM) and by X-ray diffractometry. The corrosion resistance
of the differently fused coatings was assessed by potentiodynamic
corrosion tests carried out in 3,5 % NaCl solution at room
temperature, using a saturated calomel electrode (SCE) as reference.
In addition, the variation of the friction coefficients in time for the two
tested coatings was determined using the pin-on-disk method. The investigations
showed that the characteristics of the inductive remelted
coating are better in comparison with the flame fused one
Forming Tendency Distribution of Oxide Inclusions in Kaplan Blade Castings
The results of theoretical and practical studies realized on Kaplan rotor
blades, cast from high steels alloyed with chromium and nickel represent
the objective of this paper. The data presented refer to the distribution
of alloy elements in the entire volume of the casting, resulted
from the chemical composition analysis, determined on specimens
taken from certain areas of the casting; the forming process and the
distribution of oxide inclusions during the mould filling process and during
the solidification process. In order to obtain results we have applied
the AnyCasting simulation software. Microstructures of specimens from
four different areas of the casting are also presented in this paper
Influence at Work Distance between the Sonotrode and Specimen to Cavitational Erosion
The paper presents the results of cavitation erosion tests performed on
five samples from pure aluminum using the vibratory method with
stationary specimen. The main purpose of this research is for determine
which is the distance between the sonotrode and specimen
favorable for an aggressive cavitational attack. For this, has been calculated
the Mean Depth of Erosion (MDE) and the cavitation erosion rate
(Vec). After that the specific curve for Vec has been analytically processed
The Influence of the Printing Temperature and the Filament Color on the Dimensional Accuracy, Tensile Strength, and Friction Performance of FFF-Printed PLA Specimens
The printing variable least addressed in previous research aiming to reveal the effect of the FFF process parameters on the printed PLA part’s quality and properties is the filament color. Moreover, the color of the PLA, as well as its manufacturer, are rarely mentioned when the experimental conditions for the printing of the samples are described, although current existing data reveal that their influence on the final characteristics of the print should not be neglected. In order to point out the importance of this influential parameter, a natural and a black-colored PLA filament, produced by the same manufacturer, were selected. The dimensional accuracy, tensile strength, and friction properties of the samples were analyzed and compared for printing temperatures ranging from 200 °C up to 240 °C. The experimental results clearly showed different characteristics depending on the polymer color of samples printed under the same conditions. Therefore, the optimization of the FFF process parameters for the 3D-printing of PLA should always start with the proper selection of the type of the PLA material, regarding both its color and the fabricant