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1

Investigating the effects of alumina nanoparticles on the impact resistance of polycarbonate nano-composites

Alavi Nia Ali, Amirchakhmaghi Saeed

Archive of Mechanical Engineering

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2022

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LXIX, nr 3

431--454

EN

In this project, two types of treated and untreated alumina nanoparticles with different weight percentages (wt%) of 0.5, 1 and 3% were mixed with polycarbonate matrix; then, the impact ballistic properties of the nano-composite targets made from them were investigated. Three types of projectile noses -cylindrical, hemispherical, and conical, each with the same mass of 5.88 gr – were used in the ballistic tests. The results highlighted that ballistic limit velocities were improved by increasing the percentage of alumina nanoparticles and the treatment process; changing the projectile’s nose geometry from conical to blunt nose increases the ballistic limit velocity, and ultimately, by increasing the initial velocity of conical and hemispherical nosed projectiles, the failure mechanism of the targets changed from dishing to petalling; whereas for the cylindrical projectile, the failure mode was always plugging.

2

Unraveling the effects of surface preparation on the pitting corrosion resistance of austenitic stainless steel

Sohrabi M. J., Mirzadeh H., Dehghanian C.

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 1

99--108

EN

The effects of surface preparation on the corrosion resistance of AISI 316L austenitic stainless steel were studied using the cyclic potentiodynamic polarization method. Grinding, mechanical polishing, and electropolishing were considered as the surface modifier methods. Regarding the surface roughness parameters, besides the conventional height parameter (Ra), the kurtosis (Rku) as the shape parameter was also considered to rationalize the pitting resistance for the first time. Based on the results of the Tafel extrapolation method, it was revealed that the uniform corrosion can be adequately correlated to Ra. However, the pitting resistance was found to mainly relate to the kurtosis, where by decreasing Rku (increased bluntness of topographic features), the pitting resistance enhanced. It was also found that a surface with Rku less than three (platykurtic) is resistant to pitting attack, where this surface can be obtained via electropolishing performed for an optimum time. The effect of electropolishing on the chromium content at the surface and its relation to the corrosion properties were also discussed.

3

New possibilities of shaping the surface properties in austempered ductile iron castings

Myszka D.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 1

103--106

EN

The paper presents recent developments concerning the formation of surface layer in austempered ductile iron castings. It was found that the traditional methods used to change the properties of the surface layer, i.e. the effect of protective atmosphere during austenitising or shot peening, are not fully satisfactory to meet the demands of commercial applications. Therefore, new ways to shape the surface layer and the surface properties of austempered ductile iron castings are searched for, to mention only detonation spraying, carbonitriding, CVD methods, etc.

4

Investigation of the effects of various surface treatments on properties of plastic mould steels X40CrMoV5-1

Meran C., Sarikaya E.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 1

54--58

EN

Purpose: CrN coating, hard chrome plating and nitriding has been applied on commonly used thermoset plastic mould steel X40CrMoV5-1 (Materials number 1.2344). The effects of these surface treatments over wear behaviour, impact behaviour, hardness, tensile strength and corrosion behaviour experimentally investigated. Design/methodology/approach: Charpy test, tensile test, hardness measurements, wear tests, salt spray tests conducted over hard chrome plated, nitrided, CrN coated and uncoated X40CrMoV5-1 specimens. Coating thickness and diffusion layers examined by Nikon Eclipse LV150 optical microscope. Findings: Highest micro hardness was observed in CrN coating, which is followed by nitriding and hard chrome plating. In wear tests, highest wear resistance was observed in CrN coating, then nitriding. Hard chrome plated samples were exposed abrasion more than uncoated ones. CrN coating and hard chrome plating didn’t affect the yield and tensile strength of material but increased the modulus of elasticity. It is observed that, nitriding decreased the tensile strength but increased the modulus of elasticity. Decrease in impact energy, and increase in brittleness was observed in descending order of nitriding, CrN coating and hard chrome plating. Research limitations/implications: Tensile test machine with hydraulic jaws can be used in further researches. Practical implications: Suitable surface treatment selection in X40CrMoV5-1 mold steels can be made more accurate by using spider diagrams which found in this research. Originality/value: This study was performed in the frame of the Pamukkale University Scientific Researches Projects Coordination Unit project no 2010FBE036 „Investigation of the Effect of Various Surface Treatments on Properties of Plastic Mold Materials”.

5

Hydrogen Embrittlement Control of Metallic Screws after the Surface Treatments by Wedge Test

Bezecný J., Šišáková J., Bakošová D.

Machine Dynamics Research

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2010

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Vol. 34, No. 3

21-28

EN

By surface treatments can occur so called hydrogen embrittlement, which is proving the cracking of joining pieces. Embrittlement on the critical value is predicated by several factors and therefore is important the concretization to admit the effective curative proceeding. Most parts produced of construction steels are exposed not only the mechanical straining but also the action of aggressive environment during its service. Common used protection is the galvanic metallization. However it impending degradation dangerous of useful properties so called hydrogen embrittlement by the surface treatments. By this time doesn't exist the definitive explanation what mechanism causes the hydrogen degradation of useful properties. At the same time is not achieved the efficiency of technologically precautions the eliminated the possibly degradation of useful properties parts influenced by hydrogen. The purpose of this paper was to verify and practically realized the method of steel hydrogenization control after the heat treatment according to ISO/DIS 10587. The test apparatus comprise of the steel wedge by angle of 6° and the filling steel plate. The test consists of screw tightening on moment, its cracks controlling and observing of number of hours leading to fracture. The experimental confirmed that the method of inclined wedge is an applicable method for material hydrogenization process on the critical value. The advantage is for state if the screws of same production runs are applicable by this standard, there can be fitted into a processing. By materials tests were occurred that for hydrogen process on critical value has the most influence the bating process realized before the surface treatments. However, after this operation is impossible the dehydrogenization of parts. The meaningful influence has also the radiuses in the critical parts which can affect as the notches and stress raisers.

6

Mechanical characterization of the interface between a shape memory alloy fiber and a resin epoxy matrix

Thiebaud F., Gabry B., Lexcellent C.

Engineering Transactions

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1998

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Vol. 46, iss.3/4

290-314

EN

The aim of this paper is to characterize the interface between a shape memory alloy wire (SMA) and a epoxy resin matrix. Herę we present the effect of various surface treatments applied to SMA NiTi wires on the ąuality of the interface fiber/matrbc. First, the use of the fiber pull-out test allows to separate the different treatments into two families: on the one hand, decohesion of the wire; on the other hand, rupture of the wire before debonding. The data given by the pull-out tests are not sufficient to differenciate the surface treatments which cause the breaking of the wire rather than the interfacial debonding of the fiber/matrbc. In order to complete our research, a topographical study is carried out on different wires. It allows us to extract the parameters which characterize the vertical distribution of roughness and its morphology. The analysis of these experimental results leads to the choice of the surface treatment which will guarantee higher interfacial stresses. Among all the wires studied, we choose the prestrained wire. The quantitative aspect of this study allows us to know better the evolution of the different parameters of roughness, and thus to guide our research works to an optimal surface treatment of the wire.