7 Lecture Room III

Lecture Room - III Metallurgy & Material Engineering

Metallurgy & Material Engineering

30

Scanning Electrochemical Microscopy:

A new way forward to identify and quantify regions of different electrochemical

activity at high velocity oxyfuel sprayed Inconel 625 coatings

Akbar Niaz Butt Institute of Chemical Engineering and Technology, University of the Punjab, Lahore.

Abstracts

The scattered electrochemical activity at HVOF sprayed coatings is well known and studied by

different researchers by using electrochemical techniques i.e., OCP vs. time measurement,

potentiodynamic polarization, electrochemical noise and impedance spectroscopy. The real

problem with existing techniques is that they do not give the precise position of the varied

electrochemical activity over the surface. Furthermore results produced from the existing

electrochemical techniques come with inherent errors of charging current, ohmic losses and other

background currents. In the present study we used a more sophisticated technique; scanning

electrochemical microscopy to spatially resolve and quantify regions of different electrochemical

activity over HVOF sprayed Inconel 625 coatings. The SECM imaging was used to locate the

positions of different electrochemical activity. Furthermore kinetics of charge transfer across

substrate/electrolyte interface was studied to quantify different regions of electrochemical

activities. In SECM analysis a 25µm diameter microelectrode was used to scan electrochemical

activities of Inconel 625 coating in 0.1 M K2SO4 containing 1 mMferrocenemethanol as a redox

mediator. The bulk Inconel 625 alloy was used as a reference to establish comparison. The

SECM images of the coatings showed segregated regions of low and high currents whereas the

bulk alloy presented same current all over the surface. The electron rate constant was measured

between 2.01 × 10-4 cm s−1 to 5.25 × 10-4 cm s−1 for the coating and 1.2 × 10-3 cm s−1 over

the bulk alloy surface. These results clearly demonstrated that SECM can be used to visualize

and quantify active regions having different electrochemical activity at HVOF sprayed coatings.

5th Symposium on Engineering Science (SES) Wednesday April 2, 2014

31

Friction Stir Welding: Overview and Applications

SaleemKhosa1+

, S. Jan, M. Munir, M. Kaleem++

+Pakistan Institute of Engineering and Applied Sciences (PIEAS), PO Nilore, Islamabad ++

Pakistan Atomic Energy Commission (PAEC), PO Box 1356, Islamabad

Abstract

Friction Stir Welding (FSW) is a relatively novel joining technique which was invented by The

Welding Institute (TWI), UK in 1991 [1]. Major advantage of this method is of being a solid

state welding technique i.e. unlike in conventional welding procedures, no melting is involved

during this process. Moreover no filler material and special edge preparation requirements give

this method an environmental and economic edge over other methods of welding [2, 3].

In this presentation following main agendas shall discussed:

1. An overview of the FSW process

2. Extent of its application domain and

3. Review of feasibility studies

1Email: [email protected]

mailto:[email protected]


32

An Innovative Reaction Model Determination Methodology in Solid State

Kinetics based on Variable Activation Energy

Muhammad Azeem Arshad2

Faculty of Sciences, University of Mohammed V Agdal, Rabat, Morocco

Abstract

Determination of appropriate reaction model(s) in solid state reactions has been confronting with

serious discrepancies over the decades. The dilemma in the choice of reaction models originates

from the use of oversimplified methods to handle the complicated multi-step kinetics. In order to

minimize these discrepancies, an advanced reaction model determination methodology is put

forward which deals with variable energy of activation concept. This methodology is expected to

fairly simulate single step as well as multi-step reaction kinetics. The fresh expressions for the

well known reaction models under this methodology are derived and their validity conditions are

discussed. The methods for determining pre-exponential factor(s) in single step and mutli-step

processes are also reviewed. The precautions while using the said methodology and its

prospective applications are also discussed.




33

Work-Piece Material (AA6082-T6) Response during Friction Stir Spot

Welding (FSSW) Process

Muhammad Asad Meraj3+

, Saleem Khosa++

, Thomas Weinberger+++

, Norbert Enzinger++++

+COMSATS Institute of Information Technology, Sahiwal, Pakistan

++ Pakistan Institute of Engineering and Applied Sciences (PIEAS), PO Nilore, Islamabad, Pakistan

+++Stirzone GmbH, Graz, Austria

++++ Institute of Materials Science and Welding, Graz University of Technology, Austria

Abstract

Friction Stir Welding (FSW) and its variant Friction Stir Spot Welding (FSSW) are solid state

welding techniques. These procedures rely on the transition of work-piece material from a solid

mechanic to a rheological visco-plastic one, to join the faying surfaces. Thermal softening and

work hardening are the competitive phenomena until these establish a dynamic equilibrium as

the behavioral mechanism during this process.

In this presentation this dynamic behavior of work-piece for AA6082-T6 material is discussed.

Some results for theoretical investigation and its experimental validation are presented using

Finite Element Method to develop a 3D coupled Thermo-mechanical process model for FSSW.




34

Synthesis and Characterization of multifunctional γ-Fe2O3, MnO coated Ag

Doped nano particles by sono chemical method

Abdul Wahab, Kashif Mairaj Deen

Abstracts

Super paramagnetic behavior of iron oxide has been commonly used in various application such

as magnetic resonance imagining, repairing of tissues , drug delivery system, detoxification of

blood cells and coating of shielding materials etc. All these biomedical application needs particle

size less than 100nm, high surface area is required which gives better chemical and physical

adsorption properties. A simple chemical route for the synthesis of γ-Fe2O3 nanoparticles by

dispersion in 30% ammonium solution by sonication has been adopted in this study. Magnetic

properties are improved with MnO coating. Which stabilize γ-Fe2O3 in normal conditions.

Doping of Ag is done to modify the surface characteristic. The coated doped γ-Fe2O3 are

characterize by using physical techniques XRD, SEM, FTIR and particle size analysis. The

characterization technique validated that the particles obtain by wet precipitation method are

homogeneous in structure and have a particle size less than 20nm


35

Failure Investigation of waste Heat Recovery Boiler

in a Nitric Acid Production Plant

Umair Hussain Shah, Waqar Ahmad, Hamd Mazhar, Kashif Mairaj Deen, Taqi Zahid Butt College of Engineering and Emerging Technologies, University of the Punjab, Lahore

Abstracts

The repeated failure of waste heat recovery boiler (WHRB) coupled with ammonia oxidation

reactor in a fertilizer plant is investigated in this study. Failure was observed in the boiler shell

where thickness was 14mm constructed with 1Cr-0.5Mo (SA 204 Grade A) steel. After 289080

hours operation a failure was observed at the upper vessel section and working at temperature

500 - 600oC and internal pressure of 5.5kg/cm2. Air/ammonia mixture was being fed in the

reactor coupled with WHRB and as a result of the exothermic reaction of ammonia oxidation the

temperature was raised to 800oC in reactor. To recover this heat a steam was being introduced at

a pressure and temperature of 42kg/cm2 and 135⁰C respectively having flow rate of 300m3/h in

WHRB. The temperature raised during NOX production was reduced to 280oC and pressure 5

kg/cm2 by this steam. The scale thickness on the inner side of the boiler shell was calculated to

estimate Larson Miller Parameter (LMP) which in turn was used to predict the temperature of the

shell at the time of failure. The spheroidization and triple point cracks were observed in the

microstructures which validated the long term creep failure. The major crack was intergranular

and growth was along the embrittled grain boundaries. It was found that the failure occurred in

the upper section of WHRB shell corresponded to prolong heating and overheating beyond the

design limits.


36

Recent Advances in Transmission Electron Microscopy (TEM)

Specimen Preparation

Dr. AqilInam4

Department of Metallurgy and Materials, CEET, University of the Punjab, Lahore

Abstracts

Conventional TEM specimen preparation techniques are not site-specific. SEM becomes a very

powerful tool when equipped with a focused ion beam (FIB) column for both characterisation

and micro-milling (machining) of material. A Dual beam FEI Nova 200 Field Emission Gun

Scanning Electron Microscope (FEGSEM) with a FIB column has been used for preparing FIB

Lamellas of regions containing graphite particles for subsequent study by transmission electron

microscopy (TEM). The FIB beam is used for micro-milling of the specimen whilst the SEM

beam is used for watching progress of the machining operation.

FIB-SEM is an excellent tool for preparing FIB Lamellas especially for subsequent TEM

characterisation of precipitate phases in metallic alloys. The unique advantage of this technique

is that it is possible to locate and identify a precipitate by SEM imaging and EDX analysis, and

then produce a FIB/TEM Lamella containing it for TEM study. EDX analysis, elemental maps,

HRTEM lattice images and diffraction patterns are taken from the FIB Lamellas containing

graphite particles.

4 Invited Lecture


37

Interfacial Conditions Heat Generation during

Friction Stir Spot Welding (FSSW) Process

Saleem Khosa5

Pakistan Institute of Engineering and Applied Sciences (PIEAS), PO Nilore, Islamabad

Abstract

Friction Stir Spot Welding (FSSW) is a solid state welding technique which depends upon

frictional and deformational heat input developed during the process. Both these mechanisms of

heat input are considered to be caused by the interfacial conditions between the welding tool and

the work-piece. These conditions are generally studied using theoretical investigations based

upon solid mechanics or fluid dynamics.

In this presentation, a solid mechanics approach is presented to formulate a physical based

definition for fictional co-efficient. Since this co-efficient plays the key role in Coulombic

description of frictional heat input therefore a physical approach to define this co-efficient may

be expected to improve the mechanism understanding of this relatively new welding technique.




38

Treatment of cyanide of flue gases of Metallurgy industries by

Alkaline Scrubbing in Plastic Packing

Gulam Abbas6, Muhammad Shahbaz, Muhammad Sajid

7Muhamamd,

Muhammad Tariq, Sulemantahir8

Department of Chemical Engineering, University of Gujrat

Abstract

Mineral play key role in development of world.Demand of metals increasing day by day due to

increasing of manufacturing production. After mining, metal are extracted from ore, metal and

extraction of metals is increasing day by day. During extraction of metals from ore in metal

industry flue gases emitted which comprises of many toxic component. In this study we have

gone through a real problem of industry. Cyanide is most toxic in flue gases of metallurgical

industry which polluted environment and creating health issue. A plant is producing 200,000

metric ton of metal per year and 2363 Kg/hr of flue gas with 54,794,520 mg/hr of cyanide. This

quantity of cyanide is very high and above EPA and OSHA standards. Alkaline scrubbing used

in which NaOH used alkaline scrubbing agent due to its cheap then KOH. Use of plastic packing

shows good results because it does not react with alkaline material. Cyanide reduced to

20,092mg/hr or 0.2mg/m3 is not effected environment.

6Email: [email protected] 7Email: [email protected] 8Email: [email protected]





39

Corrosion Inhibition of 316L Stainless Steel in Plain Tap Water

Anaum Nawaz, Ameeq Farooq, Kashif Mairaj Deen, Rafiq Ahmad

CEET, University of the Punjab, Lahore

Abstracts

The corrosion behavior of 316L stainless steel in the presence of various Cl- ions concentrations

at constant dose (ZOP) inhibitor has been investigated electrochemically by Tefal Scan,

Potentiodynamic, Cyclic polarization and Electrochemical Impedance spectroscopy (EIS). These

techniques evaluated that the probability of pitting to occur and effect of ZOP inhibitor on pitting

resistance. The corrosion inhibition by (ZOP) was due to formation of passive film which

obstructed the approach of aggressive anions at the surface. The effect of ZOP inhibitor was

more pronounced at 100ppm Cl- ions concentration. Increase in Cl- ion concentration in solution

not only shifted the pitting potential towards negative direction but also adversely affected the

inhibitor efficiency of ZOP which resulted in high corrosion rate.


40

Effect of Heat Treatment on Microstructure and Corrosion Behavior of

AISI 1020, 1045 and 4340 Steels

H. M. Fida, M. Sajjad, M. Ejaz, A. A. Khan, A. Farooq, K. M. Deen Department of Metallurgy and Materials Engineering, College of Engineering & Technology,

University of the Punjab

Abstract

AISI 1020 steel is used in case hardened condition for simple structural applications. AISI 1045

is widely used for industrial applications requiring wear resistance and high strength. AISI 4340

alloy steel is mainly used in power transmission gears, shafts, and aircraft landing gears.

Annealing, normalizing and quenching heat treatment was carried out on these steel grades. The

metallography of these heat treated samples to reveal microstructural details was conducted. The

electrochemical techniques were used to evaluate the corrosion behavior as a function of heat

treatment procedure and microstructural details. Corrosion potential and Potentiodynamic

polarization technique was used to investigate corrosion tendency and kinetic behavior of heat

treated samples in saline solution. It was deduced that corrosion rate was decreased sequentially

after quenching than annealing and normalizing.

Keywords: Steels; Heat treatment; Microstructure; Corrosion; Electrochemical


41

The Development and Characterization of Fiber Metal Laminate for the

Air Craft and Cargo Industry

Abdul Waji Faruki, Nauman Anwar, K. M. Deen Department of Metallurgy & Materials Engineering, CEET, University of the Punjab, 54590, Lahore, Pakistan

Abstract

From last ten years, increasing demand in aircraft industry for high-performance, lightweight

structures have stimulated a strong trend towards the development of refined models for fiber-

metal laminates (FMLs). Lower structural weight enables the down-sizing of propulsion system

and thus decreasing manufacturing and operating cost as well as has reduced the environmental

impact. Fiber metal laminates are hybrid composite materials built up from interlacing layers of

thin metals and fiber reinforced polymers.

Fiber metal laminates (FMLs) like Hybrid (Carbon Glass fiber reinforced aluminum laminate),

GLARE (Glass Fiber Reinforced Aluminum Laminate), based on high strength glass fibers,

CARALL (Carbon Fiber Reinforced Aluminum Laminate), based on carbon fibers and

CARGALL (Carbon Reinforced Glass Fiber Aluminum Laminate) were developed in a

hydraulic press coupled with autoclave. The hybrid nature of these produced composites would

provide several advantages such as better toughness, resistance to fatigue crack growth and

strength especially for aircraft applications.

Satisfactorily impressive tensile test results were obtained having high yield and tensile strength

values. X ray images confirmed the excellent adhesion b/w the metal and fiber layers without

having defects such as voids, entrapped bubbles and free spaces.

Keywords: Laminated Composite; Fiber; Strength; Defects

Documents

7 Lecture Room III