Formation of Tensile Stress Induced Cracks in Flame Hardening Surface Treatment of 12Cr Blade Steel

This paper reports on the formation of tensile stress induced cracks by the application of a flame hardening to 12Cr steels and the monitoring of the flame hardening process at the desirable residual stress state. During the flame hardening of the steels elastic residual tensile stresses were typically generated due to a phase transformation of austenite into martensite and they became greater by increasing both the process temperature and cooling rate. Eventually the cracks were nucleated and propagated across the prior austenite grain boundaries by a generation of large tensile stress, which was accompanied by a drastic decrease in the tensile stress due to a stress relaxation.

Download Full-text

Particulate Reinforcement of Polyacrylate Elastomers. II. Mechanical Properties

Rubber Chemistry and Technology ◽

10.5254/1.3539690 ◽

1975 ◽

Vol 48 (5) ◽

pp. 830-844 ◽

Cited By ~ 1

Author(s):

D. C. Blackley ◽

M. W. Sheikh

Keyword(s):

Mechanical Properties ◽

Tensile Stress ◽

Surface Treatment ◽

Strain Curve ◽

Glass Beads ◽

Void Content ◽

Scanning Electron Micrographs ◽

Stress Strain ◽

Test Pieces ◽

The Matrix

Abstract This paper presents and discusses the mechanical properties of crosslinked poly (ethyl acrylates) containing various amounts of microscopic glass beads. The adhesion between the glass beads and the elastomer matrix was varied by subjecting the beads to different surface treatments. That the adhesion is affected by surface treatment has been demonstrated in two ways: (1) Unfilled elastomer sheets have been cast in contact with glass surfaces which had been treated with the same reagents as the beads. The force required to peel the elastomer from the glass was then measured and found to depend strongly upon the surface treatment. (2) Scanning electron micrographs of the ruptured surfaces of used tensile test pieces cut from filled elastomer sheets confirm that surface treatment has a profound effect upon the adhesion between bead and matrix. Results are presented for the hardness and tensile stress-strain properties of elastomers containing various amounts of beads. In all cases, the stiffening effect of the beads increases as the adhesion between beads and matrix is improved. Beads which had been treated in such a way as to minimize the adhesion to the matrix were found to cause an apparent softening of the material as revealed by the tensile stress-strain curve. It has been shown that this effect can be satisfactorily explained if it is assumed that in this case the beads merely serve to increase the void content of the material.

Download Full-text

Contact Stress Analysis During Fretting of a Surface Modified Flat-on-Flat With Round Edge

Volume 12: Advanced Materials: Design, Processing, Characterization, and Applications ◽

10.1115/imece2019-11222 ◽

2019 ◽

Author(s):

Pankaj Dhaka ◽

Raghu V. Prakash

Keyword(s):

Elastic Modulus ◽

Yield Strength ◽

Tensile Stress ◽

Surface Treatment ◽

Contact Pressure ◽

Normal Load ◽

Contact Geometry ◽

Parent Material ◽

Tangential Displacement ◽

Element Analysis

Abstract In the present work, a two-dimensional finite element analysis is carried out to understand the influence of contact geometry and surface treatment on the fretting behavior of a flat with round edge-on-flat plate contact. The fretting pad and plate are modeled using isotropic elastic material properties of Ti-6Al-4V. The mating pair was subjected to a constant normal load followed by a tangential displacement. The effect of contact geometry was studied by independently varying length of the central flat region and radii of corners. Parameters important from the context of fretting viz. contact pressure and normal stress (in tangential direction) were extracted. The effect of surface treatment was studied by modeling two layers of different elastic modulus and yield strength on the mating surfaces. It is found that addition of intermediate layers of lower elastic modulus and yield strength than the parent material leads to a reduction in both contact pressure and peak tensile stress; the influence was more on the peak tensile stress than contact pressure. Further, the addition of softer and less stiff layers on the pad is noted to be less advantageous than adding it on both pad and substrate or substrate only case. The study suggests that contact geometry should be taken into account while carrying out surface modifications of contact pairs.

Download Full-text

Rancang Bangun Teknologi Automatic Surface Treatmen Untuk Meningkatkan Ketahanan Jalan Rel Kereta Api

Jurnal Perkeretaapian Indonesia ◽

10.37367/jpi.v5i1.129 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Willy Artha Wirawan ◽

Tumiran Anang Cundoko ◽

Hari Boedi Wahjono ◽

Fadli Rozaq ◽

Sunardi ,

Keyword(s):

Surface Treatment ◽

Program Control ◽

Software Program ◽

Flame Hardening

Batang rel berfungsi sebagai penahan berat beban dari rangkaian kereta api yang berjalan diatasnya. Berat yang besar pada rangkaian dapat mengakibatkan gesekan dan keausan yang berlebihan sehingga dibutuhkan permukaan rel yang keras dan tahan terhadap keausan. Tujuan pada penelitian ini adalah rancang bangun prototype alat yang berfungsi sebagai upaya meningkatkan ketahanan pada permukaan jalan rel kereta api. Metode yang digunakan pada konsep penelitian ini dengan teori flame hardening yaitu dengan pemanasan rel kereta api menggunakan gas oxy-asetilen kemudian dilakukan quenching secara cepat untuk meningkatkan kekerasan pada permukaan rel kereta api. Pembuatan prototype dimulai dengan perancangan hardware yang meliputi alat Surface Treatment dan perancangan perangkat software program control automatic. Hasil prototype dilakukan uji fungsi keberhasilan alat yang dapat dioperasikan dengan baik menggunakan mode manual dengan kecepatan maksimal 0.1 m/s dan mode otomatis 0.08 m/s.

Download Full-text

Failure of the Asphalt–Aggregate Interface under Tensile Stress: Insight from Molecular Dynamics

Journal of Materials in Civil Engineering ◽

10.1061/(asce)mt.1943-5533.0003601 ◽

2021 ◽

Vol 33 (3) ◽

pp. 04021008

Author(s):

Zhao Du ◽

Xingyi Zhu ◽

Feng Li ◽

Siqi Zhou ◽

Ziwei Dai

Keyword(s):

Molecular Dynamics ◽

Tensile Stress

Download Full-text

Surface treatment with silver particles isles on Titanium cp: study of antimicrobial activity

Research Society and Development ◽

10.33448/rsd-v9i4.2662 ◽

2020 ◽

Vol 9 (4) ◽

pp. e27942662

Author(s):

Patrícia Capellato ◽

Cláudia Eliana Bruno Marino ◽

Gilbert Silva ◽

Lucas Victor Benjamim Vasconcelos ◽

Rodrigo Perito Cardoso ◽

...

Keyword(s):

Antimicrobial Activity ◽

Surface Treatment ◽

Titanium Surface ◽

Silver Clusters ◽

Silver Particles ◽

Silver Deposition ◽

Dispersed Particles ◽

Significant Difference ◽

Diffusion Assay ◽

Antibacterial Potential

During the last decades, researchers have been growing the interest in surface treatment with an antimicrobial agent. Silver nanoparticles (AgNPs) are widely used in biomedical fields due to their potent antimicrobial activity. So, in this study was investigated silver particles (isles) coated on titanium surface for dental and orthopedic application. Silver particles coating process on titanium surface were performed via sputtering that is a plasma-assisted deposition technique with and titanium without treatment was applied as comparing standard. Plasma treatment parameters were optimized so that the result was not a thin film of Ag but dispersed particles of Ag on the Ti-cp surface. The alloy surfaces were investigated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). In order to investigate antibacterial potential Staphylococcus aureus and Escherichia coli have been used at Agar diffusion assay. The results were analyzed by analysis of variance (ANOVA) in order to verify significant difference antimicrobial activity between samples that have shown no difference between the surfaces studied treatments. For silver deposition scattered particles (isles) over titanium surface for a 10-minute treatment, EDS revealed by silver clusters that the particles were not properly scattered onto surface, hence, the low effectiveness in antibacterial activity.

Download Full-text