Scanning Electron Microscopy@UNIMAP

2019-06-24T21:29:00.001-07:00

COATING PROCEDURE FOR EXTERNAL APPLICATION

2019-03-08T02:30:00.000-08:00

BORANG SEM FTK KIMIA

2019-02-13T00:09:00.002-08:00

Hubungi Kami

2019-02-07T23:58:00.003-08:00

PEGAWAI BERTANGGUNGJAWAB UNTUK ALATAN SEM (2018/2019)

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Urusan Pembayaran:

1. Dr. Khairul Anwar Abdul Halim

(kanwar@unimap.edu.my; 012-6659871)

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Urusan Tempahan Tarikh Slot:

1. Dr. Lim Bee Ying
(bylim@unimap.edu.my)

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Urusan Pengendalian SEM (Juruteknik)

1. En. Mohamad Zahirrudin Mohamad Pusfa
(zahirrudin@unimap.edu.my; 018-4674658)

2. Mohd. Aizat Abd. Rahman
(mohdaizat@unimap.edu.my; 012-514 7030)

3. En. Syed Aqil Syed Mustaffa
(syedaqil@unimap.edu.my; 012-4899336)

4. En. Mohd. Faisal Rusli
(faisalrusli@unimap.edu.my; 012- 4169394)

PERATURAN BERKAITAN SEM [Rules Regarding SEM]

2019-02-07T22:40:00.001-08:00

Booking Table for Universal Testing Machine (Tensile)

2015-03-13T00:52:00.000-07:00

Booking Table for FESEM

2015-03-09T17:32:00.002-07:00

PENGUMUMAN

Assalamualaikum & Sejahtera.
Saya ingin maklumkan bahawa mesin FESEM tidak dapat digunakan dalam masa terdekat. Ini adalah disebabkan kegagalan pam vakum berfungsi dengan baik. Pihak Crest (pembekal) sudah dimaklumkan dan akan datang untuk menyelesaikan masalah mesin secepat mungkin.

Sekian untuk makluman.
Hadzrul

OES form (English)

2012-03-27T02:09:00.001-07:00

Simply right click & save image. Then paste to MS word & print

Borang OES (Bahasa Melayu)

2012-03-27T02:01:00.001-07:00

Klik kanan & save imej. Tampal dlm MS Word & cetak

Secondary detector

2011-03-29T23:49:00.000-07:00

Secondary electron detector in SEM Chamber

The secondary electron (SE) detector allows the topographic features of (gold or carbon) coated samples to be imaged. The resolution of the SE detector is 3.5nm at 30kV, enabling very fine detail to be resolved. Using the secondary electron detector produces a clear and focused topographical image of the sample.

Example 1: Ecthed microstructure

Figure 1: This secondary electron SEM image shows the cementite delineating prior austenite grain boundaries with a thin layer. The amount of proeutectoid phase is very low, with the majority of the area being taken by the pearlite eutectoid. Again each pearlite cell has a different orientation with the ferrite phase being selectively etched.

Image 2: Fractured surface

Figure 2: This is an image of the broken surface of a piece of metal, formed using secondary electron imaging.

It is note that sometimes it is not suitable for polished sample observed under the SEM using secondary electrons, except if you use a higher magnification view, or you want to test the presence of certain elements using EDS. The analysis will get better or meaningful result by using optical/ metallurgical microscope by metallography technique.

The SEM objective lens

2011-03-29T23:22:00.000-07:00

The SEM objective lens

The lens that focuses the beam of electrons towards the sample is in the center of the picture. The parts off to the right of the sample are different detectors. One is for detecting the secondary electrons and the other is for detecting the backscattered electrons. The operator has the power to choose and switch detectors for use on each sample.

Electron / Specimen Interactions

2011-03-29T22:19:00.000-07:00

When the electron beam strikes the sample, a large number of signals (shown in Fig. 1 are generated. We can divide the signals into two broad categories:

a) electron signals

b) photon signals.

Figure 1: The signals generated when electron beam strikes the sample

While all these signals are present in the SEM, not all of them are detected and used for information. The signals most commonly used by SEM are the Secondary Electrons, the Backscattered Electrons and X-rays. The specimen interaction volume (shown in Fig. 2) is the volume inside the specimen in which interactions occur while interacting with an electron beam. Therefore we can know SEM is a kind of surface characterization.

Figure 2: Specimen interaction volume

Scanning electron microscope (SEM) & how it works

2011-03-22T03:39:00.000-07:00

The scanning electron microscope (SEM) is a type of electron microscope that images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. The electrons interact with the atoms that make up the sample producing signals that contain information about the sample's surface topography, composition and other properties. Magnification in a SEM can be controlled over a range of up to 6 orders of magnitude from about 19X to 300,000X.

Figure 1: Basic SEM Setup and its electron path

How does SEM work? A beam of electrons is generated in the electron gun, located at the top of the column, where a filament is located. The most common used filament is Tungsten hairpin gun. This filament is a loop of tungsten which functions as the cathode. A voltage is applied to the loop, causing it to heat up. The anode, which is positive with respect to the filament, forms powerful attractive forces for electrons. This causes electrons to accelerate toward the anode. This beam is attracted through the anode, condensed by one or two condenser lens, and focused as a very fine point on the sample by the objective lens. The beam passes through pairs of scanning coils or pairs of deflector plates in the electron optical column. The scan coils are energized (by varying the voltage produced by the scan generator) and create a magnetic field which deflect the beam horizontally and vertically so that it scans in a raster fashion over a rectangular area of the sample surface. When the primary electron beam interacts with the sample, the electrons lose energy by repeated scattering and absorption within a teardrop-shaped volume of the specimen known as the interaction volume, which extends from less than 100 nm to around 5 µm into the surface. The size of the interaction volume depends on the electrons' landing energy, the atomic number of the specimen and the specimen's density. The energy exchange between the electron beam and the sample results in the emission of electrons and electromagnetic radiation, which can be detected to produce an image.

How does a scanning electron microscope works and what is an SEM? As told by professor Goodlove from NanoMission.org

ROLE OF SCANNING ELECTRON MICROSCOPE (SEM) IN METAL FAILURE ANALYSIS

2011-03-20T07:32:00.000-07:00

ABSRACT

Abstract Scanning electron microscope (SEM) is a scientific instrument that uses a beam of highly energetic electrons to examine the surface and phases distribution of specimens on a micro scale through the live imaging of secondary electrons (SE) and back-scattered electrons (BSE). One of the main activities of SEM Laboratory at MINT is for failure analysis on metal part and components. The capability of SEM is excellent for determining the root cause of metal failures such as ductility or brittleness, stress corrosion, fatigue and other types of failures. Many of the requests for failure analysis are from local petrochemical plants, manufacturers of automotive components, pipeline maintenance personnel and engineers who involved in the development of metal parts and component. This paper to discusses some of results of work in failure analysis associated with SEM.

INTRODUCTION

Failure analysis is the evaluation of information pertaining to the failure of a mechanical or structural component. In failure analysis, careful examination of the failed component, its design, its fabrication and its operating history can help to explain how and why a component failed. Failed parts are usually disposed without attempting to determine the causes of the failure. Because of these, failure rates and the costs associated with maintenance are high. The value of failure analysis lies in their ability to identify corrective actions by determining the causes of the failure. These corrective actions will minimize future failures of the same type. The failure analysis thus is a tool that can be used to reduce maintenance costs, increase system availability, and reduce the enormous potential losses involved in catastrophic failures. Failure analyses can also be used to identify the party at fault. Financial losses resulting from a failure can often be recovered when deficiencies in design, workmanship or materials can be identified.

One of the most important instruments used to carry out failure analysis is scanning electron microscope (SEM). It is used primarily for the study of topographic and morphological characteristics of any material. The important of SEM in failure analysis is due to its ability to provide three-dimensional image for the purpose of fractographic study where the depth of field is needed on an irregular fracture surface (De Carvalho et al., 2003). SEM capability is greatly enhanced when used together with an energy dispersive x-ray spectrometer (EDS) allowing simultaneous analysis of both sample features and their chemical compositions. This facility is made available in MINT through acquisition of a new SEM FEI Quanta 400 commissioned last year. The overall objective of this paper is to provide background information on the role of SEM for studying the fracture surface features in failure analysis and procedure preformed by operator at SEM laboratory to study failure analysis.

ANALYSIS PROCEDURE

When failed components are received in the laboratory it is customary to document their condition. This documentation usually contains overall and close-up photographs of the components and notes about the condition of the components. The failed component is then cut and sectioned without damaging the surface so that it remains as-received condition. The sample was mounted to the stub by carbon tape to maintain their conductivity without the use of gold coating. The mounted as-received samples with an appropriate size can be placed on sample holder directly in the SEM vacuum chamber. This procedure is applicable for determination of elemental composition on deposit precipitated on the sample surface. Besides that, for fractographic study, the sample usually cleaned by pickling acid to remove any dirt and the brownish rust precipitated on the sample. Morphological examination and compositional microanalysis is carried out using SEM on both as-received and cleaned samples to detail inspection on failure region of the components.

RESULTS AND DISCUSSION

After the documentation of the as-received condition and followed by nondestructive evaluation, the failed component will be subjected to detailed macroscopic examination. These examinations start with the visual examination and progress to low magnification stereomicroscope. In some cases where the fracture has an extremely irregular shape, there is a limitation when using stereomicroscope. This limitation is due to its capability to present the image in a 2 dimension form. Thus a close-up image of original condition for the fracture surface was not presentable in the report. In this case, the problem can be solved by the use of SEM. This is because of its ability not only to provide a wide range magnification up to 100,000x but also as low as 10x depends to its working distance (WD); high WD result in low magnification.

A wealth of information can be obtained from the low magnification examination for all types of failures. For failures involving fractures or cracking, the orientation of the fracture surface provides information about the stress that caused failure. For example tensile loading generally produces a flat fracture perpendicular to the stress direction with 45 degree shear lips along its edges while torsion loading produces spiral fracture surface in brittle failure and flat fracture surface in ductile failures. Fracture surface markings usually reveal the direction of crack growth and, hence, the fracture origin as shown in Figure 1. Regions surrounding the point of origin that exhibit a difference in texture are frequently observed. A multiple crack initiation sites are present along the bottom at "A", final fracture takes place just above “C”. These are indicative of a change in fracture mechanism. This is frequently the case when subcritical crack growth mechanisms such as fatigue, stress corrosion cracking or hydrogen embrittlement are responsible for the initial cracking.

Figure 1 Low Magnification SEM Macrograph of the Fracture Surface from a Failed Bolt

Low magnification examination of corrosion failures could also identify the type of corrosion (general corrosion, pitting, crevice corrosion or intergranular attack). The location and the severity of the attack and characteristics of the corrosion deposits can also be identified. Examination of wear or erosion failures can identify the location of the damage, the presence of any directionality, general surface features and the presence of surface films or deposits.

Although crack growth direction and crack initiation sites can be obtained from low magnification examinations of fractures, we may miss some of the fine scale features that are critical for identifying the fracture mode. These features can only be identified through examination at higher magnifications. The fracture features that are indicative of a specific fracture mechanism can be classified into one of four basic categories. Dimpled fracture, as shown in Figure 2(a), is indicative of a tensile or shear overload failure of a ductile material. Transgranular facets, as shown in Figure 2(b), are indicative of a transgranular brittle fracture due to cleavage or transgranular stress corrosion cracking. Intergranular facets, as shown in Figure 2(c), are indicative of brittle intergranular fracture due to embrittlement of the grain boundaries, intergranular stress corrosion cracking, hydrogen embrittlement, or high temperature grain boundary cavitation. Stage II striations, as shown in Figure 2(d), are indicative of fatigue failures. It should be noted that it is not unusual to see more than one of these features on a fracture surface. This can be indicative of a change in fracture mechanism, where a clear transition from one feature to another is present, or the simultaneous action of more than one failure mechanism, where the morphologies are clearly interspersed.

Figure 2 SEM Photomicrographs of Fracture Surfaces Exhibiting (a) Dimpled Fracture, (b) Brittle Transgranular Fracture, (c) Intergranular Fracture, and (d) Fatigue Striations

Microscopic examinations in the SEM are also useful for investigation of wear induced failure and for corrosion failure. Examination of the wear surface at high magnification can help to identify the wear mechanism while EDS can be used to identify transfer films or deposits. Examination of corroded surface using SEM is generally focused on using EDS to determine the composition of the corrosion deposits. In the case of failed wire mesh (Mohd Harun et al., 2004), the macroscopic examination of the mesh wire surface was covered with brownish rust. However the rust nevertheless can be easily cleaned using pickling acid solution. SEM micrograph and EDS analysis of brownish rust are shown in Figure 3 indicates that oxides covered the surface and the absence of corrosive agent such as chlorides (Cl) elements. This supports the fact that the surface was not attacked by any of corrosion or acidic environment.

(a)

(b)

Figure 3 SEM micrographs of (a) brownish rust on wire mesh and (b) its microanalysis EDS result.

CONCLUSIONS

Scanning electron microscope (SEM) is an important tool for microscopic examinations. Its usefulness in fractographic examinations is due to its ability to provide a wide magnification range typically from approximately 10X to 100,000X with the depth of field needed on an irregular fracture surface. Incorporation of an energy dispersive x-ray spectrometer (EDS) greatly enhances the capabilities of the SEM by providing information related to the chemical compositions of the features examined.

ACKNOWLEDGEMENT

The author(s) express their gratitude to Dr. Abd Nassir Ibrahim, Director of Industrial Technology Division and Dr. Azali Muhamad, Manager of Material Technology Group, both of Malaysian Institute for Nuclear Technology Research (MINT) meaningful discussions.

REFERENCES

De Carvalho, M. C., and de Deus, E. P. 2003. Fracture analysis of a flow control device used in the petrochemical industry. Engineering Failure Analysis. 10, (4); 423-429

Mohd Harun, Shaiful Rizam Shamsuddin, Hafizal Yazid, Mohd Shariff Sattar and Zaiton Selamat, 2004. Laboratory investigation report on wire mesh of strainer. Vinyl Chloride Sdn. Bhd., Kerteh, Terengganu. September 2004 (Technical Report - MINT/L/2004/20).

Citation:

Shaiful Rizam Shamsudin, Mohd Harun, Hafizal Yazid, , Megat Harun Al-Rasid Megat Ahmad, Siti Selina Abd. Hamid, Nadira Kamarudin, Zaiton Selamat, Mohd Shariff Sattar And Muhamad Jalil, Role Of Scanning Electron Microscope (SEM) in Metal Failure Analysis, Proceedings of MINT Technical Convention 2005, ESSET, Bangi, 15-16 Ogos 2005.

Introduction to Scanning Electron Microscope - Part 1

2010-10-12T23:59:00.000-07:00

Assalamualaikum dan Salam Sejehtera,

Disini saya ingin masukkan video Perkenalan Mikroskop Elektron Imbasan (SEM) yang telah dipersembahkan secara professional oleh Scott Braswel (Jurutera penyelidik daripada Pusat Kemudahan Pengguna Nanotech, Universiti Washington). Tujuannya adalah bagi memudahkan 1st time user mendapat overview about SEM. Namun begitu, dalam video ini tidak menggunakan Jeol SEM seperti mana SEM di Makmal PPKB, sebaliknya presenter menggunakan Sirion FEI, SEM. Namun begitu, jangan risau, mana-mana SEM adalah sama secara prinsip dan konsep bagaimana SEM bekerja.

Here I would like to add a video, Introductions to Scanning Electron Microscope (SEM) which was presented very-very professionally by Scott Braswel (a Research Engineer from Nanotech User Facility, University of Washington). The aim of this video is to facilitate the 1st time user to get an overview about SEM. However, the the presenter in this video is not using Jeol's SEM as available at PPKB Lab, on the contarary he uses Sirion SEM from FEI. But, no worries, any SEM is principally and conceptually similar on how SEM works.

Part 1 - Tour and Sample Preparation

The scanning electron microscope is used to image the surface of a conducting sample by scanning it with a high energy beam of electrons. Some SEMs have additional software enhancements than enable them to focus the beam on a photomask for E-beam lithography or are equipped for focused ion beam (FIB) milling.

This video is part 1 of a 6-part series, and gives a tour of the device, and describes how to prepare a sample.

Introduction to Scanning Electron Microscope - Part 2

2010-10-12T23:58:00.000-07:00

Part 2 - Loading the Sample

This video is part 2 of a 6-part series.

Introduction to Scanning Electron Microscope - Part 3

2010-10-12T23:57:00.000-07:00

Part 3 Setting the Working Distance

This video is part 3 of a 6-part series

Introduction to Scanning Electron Microscope - Part 4

2010-10-12T23:56:00.000-07:00

Part 4 - Lens Alignment and Stigmation

This video is part 4 of a 6-part series

Introduction to Scanning Electron Microscope - Part 5

2010-10-12T11:54:00.000-07:00

Part 5 - Moving the Stage and Imaging

This video is part 5 of a 6-part series.

Introduction to Scanning Electron Microscope - Part 6

2010-10-12T11:39:00.000-07:00

Part 6 Changing the Sample and Shutdown

This video is part 6 of a 6-part series.

Penyediaan Sampel untuk analysis Scaning elektron Mikroscope (SEM)

2010-03-03T21:45:00.000-08:00

Sebelum anda mulai persiapan sampel anda, anda perlu memastikan bahawa anda tahu maklumat apa yang ingin anda dapatkan semasa pemerhatian menggunakan SEM. Sebagai contohnya, jika anda melakukan pemerhatian bersama-sama EDS pada pada sampel yang tidak konduktif, lapisan konduktif yang anda pilih adalah menjadi penting. Dalam rangka untuk memilih kaedah penyediaan sampel terbaik, anda juga harus mempertimbangkan saiz, geometri, keadaan, dan konduktiviti sampel.

Oleh itu, jangan ragu-ragu untuk meminta kidmat nasihat daripada juruteknik/ pegawai bertanggungjawab kami yang berpengalaman, terutamanya jika anda pengguna pertama kali!

akan bersambung lagi..

Peranan Penyelia/ Supervisor Pelajar

2010-03-03T18:46:00.000-08:00

· Memastikan segala peraturan dipatuhi dan borang permohonan diisi dengan lengkap

· Mengesahkan permohonan pelajar/ pengguna

· Menasihati pelajar/ pengguna dari semua aspek untuk memohon menggunakan MIKROSKOP ELEKTRON IMBAS

· Bagi pelajar sarjana muda: Kehadiran penyelia semasa analisis MIKROSKOP ELEKTRON IMBAS dijalankan adalah diwajibkan (kegagalan penyelia menghadirkan diri semasa analisis MIKROSKOP ELEKTRON IMBAS dijalankan menyebabkan slot pengguna terbatal secara automatik)

· Ensure that all regulations are complied with and completed application form

· Approved/ reject the application from students / users under supervision

· Advising the students / users in all aspects of applying for SCANNING ELECTRON MICROSCOPE

· For undergraduate students, the presence of the supervisor during SCANNING ELECTRON MICROSCOPE analysis session is mandatory (any supervisor who failed to presence during SCANNING ELECTRON MICROSCOPE analysis affect the user slot will automatically disqualified)