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This study aims to use nanofluid-based minimum quantity lubrication (NMQL) technique to minimize the use of cutting fluids in machining of Inconel-625 and Stainless Steel 304 (SS-304) (Ni-Cr alloys).

Machining of Ni-Cr-based alloys is very challenging as these exhibit lower thermal conductivity and rapid work hardening. So, these cannot be machined dry, and a suitable cutting fluid has to be used. To improve the thermal conductivity of cutting fluid, multi-walled carbon nanotubes (MWCNTs) were added to the soybean oil and used with MQL. This study attempts to compare tool wear of coated carbide inserts during face milling of Inconel-625 and SS-304 under dry, flooded and NMQL conditions. The machining performance of both materials, i.e. Inconel-625 and SS-304, has been compared on the basis of tool wear behavior evaluated using scanning electron microscopy-energy dispersive spectroscopy.

The results indicate higher tool wear and lower tool life during machining of Inconel-625 as compared to SS-304. Machining of Inconel-625 exhibited non-consistent tool wear behavior. The tool failure modes experienced during dry machining are discrete fracture, cracks, etc., which are completely eliminated with the use of NMQL machining. In addition, less adhesion wear and abrasion marks are noticed as compared to dry and flooded machining, thereby enhancing the tool life.

Inconel-625 and SS-304 have specific applications in aircraft and aerospace industry, where sculptured surfaces of the turbine blades are machined. The results of current investigation will provide a rich data base for effective machining of both materials under variety of machining conditions.

The literature review indicated that majority of research work on MQL machining has been carried out to explore machining of Ni-Cr alloys such as Inconel 718, Inconel 800, AISI4340, AISI316, AISI1040, AISI430, titanium alloys, hardened steel alloys and Al alloys. Few researchers have explored the suitability of nanofluids and vegetable oil-based cutting fluids in metal cutting operation. However, no literature is available on face milling using nanoparticle-based MQL during machining Inconel-625 and SS-304. Therefore, experimental investigation was conducted to examine the machining performance of NMQL during face milling of Inconel-625 and SS-304 by using soybean oil (vegetable oil) with MWCNTs to achieve ecofriendly machining.

The purpose of the paper is to investigate photochemical machining characteristics of stainless steel (AISI 304-SS304) parts with a novel design are investigated experimentally from the aspect of process parameters. The effects of phototool pattern geometry, ultraviole (UV) exposure time and etching time on of AISI 304 were evaluated.

The designed semi-automated photochemical manufacturing (PCM) equipment consists of 4 units, which include UV exposure, etching, developing and surface cleaning units. Experimental procedure has been designed via Taguchi method. Results were evaluated via Analysis of Variance (ANOVA) method.

Etching time is the most effective factor in PCM quality of AISI 304 stainless steel. Surface roughness is sensitive to geometrical pattern of the phototool for PCM of AISI 304 UV exposure time is less influential on the PCM quality for stainless steel.

The designed PCM equipment prototype is not fully automated, which requires automation for part replacements into units. The effects of the temperature inside chemical processing units on process characteristics cannot be evaluated due to equipment limitations. The effects of surface cleaning time inside surface cleaning unit are not analyzed.

The utilized PCM equipment is semi-automated equipment, with which the process parameters such as etching time, surface cleaning time, UV exposure time and developing time can be controlled. Different from literature, the effects of phototool pattern geometries on the photochemical machining quality parameters are evaluated for the processing of AISI 304. The effects of processing parameters on dimensional accuracy, which is not common in the literature for AISI 304 stainless steel, are also evaluated.

The present paper seeks to report the effect of duration of rubbing on friction coefficient for different polymer and composite materials. Variations of friction coefficient and wear rate with the normal load are also investigated experimentally when stainless steel (SS 304) pin slides on different types of materials such as cloth‐reinforced ebonite (commercially known as gear fiber), glass fiber‐reinforced plastic (glass fiber), nylon and polytetrafluoroethylene (PTFE).

A pin on disc apparatus is designed and fabricated. During experiment, the rpm of test samples was kept constant and relative humidity was 70 percent.

Studies have shown that the values of friction coefficient depend on applied load and duration of rubbing. It is observed that the values of friction coefficient decrease with the increase of normal load for glass fiber, nylon and PTFE. Different trend is observed for gear fiber, i.e. coefficient of friction increases with the increase of normal load. It is also found that wear rate increases with the increase of normal load for all the materials. The magnitudes of friction coefficient and wear rate are different for different materials.

It is expected that the applications of these results will contribute to the design of different mechanical components of these materials.

Within the observed range of applied normal load, the relative friction coefficient and wear rate of gear fiber, glass fiber, nylon and PTFE are experimentally investigated.

This paper aims to study the use of electrochemical noise (EN) technology in the corrosion continuous monitoring of stainless steel (SS) in an atmospheric environment.

An EN electrode was designed and fabricated to acquire the EN of 304 SS in the atmospheric environment. The statistical analysis and shot noise analysis were used to analyze the EN, and the surface morphology analysis of 304 SS was used to verify the EN analysis results.

The activation state, passive film formation and pitting corrosion of 304 SS can be clearly distinguished by the amplitude and frequency change of EN. The metastable pitting corrosion and steady-state pitting corrosion can be identified with the shot noise parameters q and fn. Under the existence of chloride ion, the stability of 304 SS passive film decreases and the steady-state corrosion pits of 304 SS are more likely to form with the reduction of thin electronic layer (TEL) pH. The critical TEL pH of 304 SS corrosion is a pH between 3 and 4.

In an atmospheric environment, the EN technology was used in the corrosion continuous monitoring of SS.

Phosphonic acids are good complexing agents. However, they are not good as inhibitors except for a very few. Synergistic inhibition is offered in the presence of metal cations like Ca²⁺, Mg²⁺, Zn²⁺ and others in neutral media. The zinc ion is an ideal choice. The part of zinc ions are now replaced by polymers, azoles to prepare eco‐friendly inhibitor formulations. They are also used as corrosion inhibitors in concrete, coatings, rubber blends, acid cleaners, anti‐freeze coolants, etc. Discusses the various applications of phosphonic acids and their action mechanisms.

The purpose of this paper is to examine the development of aerodynamic thrust bearings and aerodynamic journal bearings applied to a small high speed cryogenic turboexpander in Indian conditions.

As a part of indigenous programme in the process of development, some input parameter was taken from the available literature and then dimensions were optimized and computed while taking care to minimize fabrication constraints.

A series of tests were conducted to confirm the findings. Detailed study of the effect of stability and vibration of bearings was taken up. The maximum rotational speed obtained was 200,000 rpm.

The outcome may help the designers, researchers and manufacturers of these components.

Although manufacturers design and develop the bearings of turboexpanders for their production, no academic literature has been available for this purpose until now.

The purpose of this paper is to investigate the erosion performance of high velocity oxy fuel- (HVOF) sprayed Al₂O₃–Cr₂O₃ composite coatings under silt slurry conditions.

The requisite HVOF composite coatings has been deposited on the stainless steel substrate (SS-304). The slurry erosion pot tester of make Ducom was used for conducting the silt slurry erosion tests on the required substrates. The comprehensive experiments were conducted at different particle size of silt in the range 212–250, 150–212, 53–106 µm, and the concentration of the silt ranged from 10%–40% by weight. The rotational speed of the pot tester has been varied between 500 and 1,500 revolutions per minute, and the test duration has been kept to 4 h.

The erosion wear resistance of the uncoated SS-304 has been greatly enhanced by the application of HVOF-sprayed Al₂O₃–Cr₂O₃ composite coatings. The addition of CeO₂ has a significant impact in reducing the erosive wear caused by silt slurry. The composite coating powder composition of 65%Cr₂O₃ + 34.5%Al₂O₃ + 0.5%CeO₂ has shown the highest erosion resistance.

The developed coatings have the potential to be used for hydro turbines as subjected to silt slurry conditions.

The erosion wear experiments are conducted comprehensively for coated and uncoated samples and the scanning electron micrographs supports the findings.

The failure of structures and components made of SS304 steel because of corrosion in the presence of saline water environment is still an unsolved issue across the globe. Conventionally, coatings and inhibitors are used to mitigate corrosion. The purpose of this study is to propose a novel method to tackle corrosion by means of micro-patterning on the surface and to explore the relation between surface morphology, corrosion and wetting nature of micro-patterned SS304 Steel.

Groove-shaped micro-patterns were created on SS304 steel surface with varying ridge and channel widths. Wettability studies conducted on flat and micro-patterned steel surfaces using high speed camera. Corrosion tests carried out in saline water using an electrochemical test set-up to quantify the performance of micro-patterned surface over flat surface and scanning electron microscopic analysis to visualize the severity of corrosion on the surfaces of SS304 steel.

Wettability studies showed that the micro-patterned steel surfaces were hydrophobic. Corrosion rates of the micro-patterned steel surfaces were lower by more than an order of magnitude compared to that of the flat steel surface. Scanning electron microscopic analysis revealed that the micro-patterned steel surfaces had less surface damage compared to the flat surface.

The author shows that the remarkable corrosion resistance shown by the micro-patterned steel surfaces is attributed to their hydrophobicity, which reduced the contact between the surfaces and the corrosive liquid media. Results from the investigation indicate that micro-patterning of SS304 steel surfaces is an effective route to decrease corrosion.

The galvanic corrosion interactions of zinc and SS.304 have been studied in a tropical marine environment over a period of 427 days, under different area ratios. The galvanic interaction of zinc and SS.304 are highlighted in terms of the corrosion rate of zinc or SS.304 resulting from galvanic coupling, and the susceptibility of zinc to pitting due to galvanic corrosion. The galvanic potential and galvanic current of the system are monitored. The corrosion products at the interface of the bimetallic contacts are analysed with XRD technique and the pitting/grooving on zinc resulting from galvanic corrosion is measured using a high resolution microscope. The weathering parameters and environmental pollutants are monitored to give an insight into the possible means of favouring the galvanic interactions. The results of the study are discussed in the light of the above factors towards predicting a mechanism for the galvanic interactions of zinc and SS.304.

The purpose of this paper is to predict the plate heat exchanger performance when axial conduction in plates and in flow channels are present and fluids' viscosities are temperature dependent.

The approach to achieve the objective of the paper is deriving the governing equations and developing a computer program based on finite differences to solve them. The governing equations become dimensionless defining reference values and then discretized using FTBCS and FTCS methods. To solve the governing equations, the flow channel is divided into small elements in axial direction. Physical properties are constant for each element, while viscosity changes from one element to another one.

The effect of axial conduction in plates as well as in flow channels on temperature distributions, are studied individually and simultaneously. The program is run under four different conditions, namely: no axial conduction, axial conduction in the plates and in the flow channels, axial conduction in the plates only, and axial conduction in the flow channels only.In all the above cases, temperature distributions are achieved and characteristic curves are plotted. The numerical results are validated by comparing them with those published in an established reference carried out ignoring the effect of axial conduction, using the same plate geometry and flow details.

This paper gives valuable information and offers practical help to plate heat exchanger design engineer in order to choose the proper material for the plates as well as the right service and product fluids.