Tag Archives: materials science

Infrared (IR) Spectroscopy

Infrared (IR) #spectroscopy is a powerful technique that allows to obtain information about the chemical structure of a variety of substances by utilizing infrared electromagnetic radiation. In this science video we will discuss the basics of this technique with the help of 3D animations and also perform a practical demonstration, where we study a Teflon substrate with ATR technique. The video was made by Captain Corrosion OÜ in collaboration with Uno Mäeorg (Associate Professor in Organic Chemistry, Institute of Chemistry, University of Tartu).

Educators can download some of the animations used in the video from our online library to enhance their courses.

Materials Characterization

Do you require more information about a certain material used in your products but don`t have the necessary equipment or knowledge?

In collaboration with the University of Tartu we can study your material with state of the art techniques in unprecedented detail and provide you with the needed information.

Contact us if you are interested in materials characterization services!

Here is a list of some common techniques used in our daily research and their possible applications:

Scanning electron microscopy (SEM) – Used to obtain high resolution images of a materials surface with a magnification far greater than in the case of optical microscopes. SEM can also be used to study the distribution of different elements in a microscopic scale or even locally (few microns area) measure the elemental composition of a material. SEM is also a valuable tool to visualize microscopic cracks and defects in a material that affect its mechanical properties. Another useful application of SEM is to study the individual grain size of powders and also evaluate the size distribution. Learn more by watching our educational video and visiting our gallery.

X-ray fluorescence spectroscopy (XRF) – Quick and easy way to precisely study the average elemental composition of various materials such as a metal alloys, ceramics and polymers. For instance, we can use XRF to verify if your supplier provides you with the metal alloy that you requested and also see if it contains any unwanted impurities. Learn more by watching our educational video.

Atomic force microscopy (AFM) – Allows to measure the roughness and surface details of extremely smooth surfaces such as glass or various fine polished materials. For example, the nano scaled roughness plays a significant role in the performance of self-cleaning windows. Learn more by watching our educational video.

X-ray diffraction (XRD) – Gives information about the crystal structure of bulk materials, powders and thin films. For instance, XRD allows to verify if a titanium dioxide powder is amorphous, anatase, rutile or a mixture. It can also give information about the effect of different thermal treatments on a metal.

Corrosion Consultation

How it Works:

Contact us and briefly describe your technological problem which related to corrosion or materials science. We will do our best to solve the problem or at least point you in the right direction.

How much does it cost?

Corrosion consultation by Captain Corrosion is for free!

However, if you are satisfied with the consultation, you can tip us via PayPal. All the money is used for making educational science videos.

Areas of Expertise:


  1. Corrosion Prevention Techniques
  2. Forms of Corrosion
  3. Protective Coatings (Metallic, Ceramic, Polymers)
  4. Rust Removal
  5. Anodizing

Materials Characterization

  1. Elemental Analysis (EDX, XRF, XPS, LEIS, LIBS etc.)
  2. Microscopy – Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Photoelectron Microscopy (SPEM) etc.
  3. Corrosion Testing – Accelerated Electrochemical Tests, Prolonged Chemical Immersion Tests


  1. Biocompatible Materials
  2. Medical Implants (e.g. Dental Implants)

About Us:

  • We are materials scientists, specialized in corrosion, biomaterials and nanotechnology.
  • We have over 7 years of experience in that field as we develop novel corrosion prevention techniques.

Low-Energy Ion Scattering Spectroscopy (LEIS)


Low-energy ion scattering spectroscopy (LEIS) is an exciting technique that allows to study the structure and chemical composition of a materials surface.

In this materials characterization method the sample is bombarded with a stream of ions and the positions, velocities and energies of the scattered ions are observed. The energy of scattered ions depends on the mass of the target, so there are distinct peaks in the energy spectrum of the scattered ions. These peaks give information about the samples elemental composition. The uniqueness of this technique lies in its sensitivity to the very first atomic layer on a sample and with forward scattering setup it is even capable of directly observing hydrogen atoms.

One of the main components of the system is the ion gun, that shoots ions at the studied substrate. The most widely used ions for that purpose are ionized noble gas or alkali atoms. Noble gas such as helium, neon or argon is ionized with electrons, giving them a positive charge. Alkali ion beams can be created by heating alkali wafers. In low-energy ion scattering spectroscopy the ions usually have an energy from 500 eV to 10 000 eV. The precise desired energy of the ions is obtained by applying a suitable accelerating voltage.

Before interacting with the substrate, the ions first need to pass through the ion beam manipulator, that narrows the beam and also filters the ions based on mass and velocity. For some experiments the ion beam is also chopped with an unipolar electrical chopper – a pulsed-wave generator, that lets through ions only when no voltage is applied. As a result the ion beam leaves the ion beam manipulator in pulses. By using short ion pulses, one can separate backscattered primary ions, for example He, from sputtered ions of different masses by time gating. This makes it possible to detect signals that would otherwise be buried in the background that is caused by ions sputtered from the sample surface.

The sample itself is attached to a special holder that allows the operator to adjust the position and angle of the sample for different experiments. When the ions hit the substrate, different interactions take place. Some ions are scattered at a certain angle and also their energy will be different after the impact. Some ions however become neutral as they pick up electrons from the substrate. The ions may also be implanted into the material or deposited on the substrate surface. The primary beam ions may also kick out electrons or atoms from the substrate and the atoms may even be ionized in the process. Radiation may also be emitted from the substrate as the excited atoms undergo a relaxation process.

The electrostatic analyzer is commonly used to detect the velocities and energies of the scattered ions. In this hemispheric device an electrical potential is applied between the inner and outer wall. The outer wall with positive potential repels the positive ions and the inner wall with negative potential attracts the positive ions. Neutral particles are unaffected by the field and hit the wall and thus never reach the detector. Positive ions with too low energy are pulled to the inner wall and also don’t reach the detector. If the cations energy is too high however then it simply hits the outer wall. Only if the ions energy is just right, it can pass through the analyzer and create a signal by interacting with the detector. By changing the potential between the walls, the operator can scan through a wide energy range in order to find out the energy of the emitted particles. In newer systems however a double toroidal analyzer is preferred as it integrates the signal over the scattering azimuth, so the intensity is some orders of magnitude higher compared to a hemispherical analyzer. The drift tube is used in TOF experiments in order to detect the energies and velocities of the scattered ionic and also neutral particles. Neutrals can easily be seperated from ions with the accelerator. There are two types of detectors that are commonly used – channel electron multipliers and microchannel plates. If the ion or a neutral particle with sufficient energy hits the detector then a cascade of secondary electrons is created and the signal significantly amplified. Microchannel plates also give information about the particles position but that comes at the cost of sensitivity.

Measurements with low-energy ion scattering spectroscopy are performed in ultra-high vacuum in order to avoid interactions with the surrounding gas. Having a good vacuum also ensures that the studied substrate and system parts are clean. Ultra-high vacuum is achieved with turbomolecular and ion pumps with the help of rough vacuum pumps.

Samples that have been exposed to open air are always contaminated for this type of surface sensitive characterization method and therefore they need to be cleaned inside the system in vacuum with appropriate equipment. Common ways to remove the contaminated top layer are sputtering, annealing or exposing to atomic oxygen.

There are of course few other surface sensitive materials characterization techniques such as XPS, AFM and SEM but each of them has distinct advantages and disadvantages. Therefore they are often used together when studying novel nanomaterials as they compensate each others weaknesses and allow to get a better overview.


X-Ray Photoelectron Spectroscopy (XPS)

Photoelectric effect, photoelectron spectroscopy (XPS) and scanning photoelectron microscopy (SPEM) are explained in this short lecture. The photoelectric effect occurs when the inner shell electrons of the sample atoms are kicked out by high energy electromagnetic radiation. These electrons, that were kicked out, are called photoelectrons and their energy depends on the energy of the exciting radiation, the electrons initial binding energy and on the work function. When having a radiation source with well defined energy and measuring the energy of the emitted electrons, it is possible to get information about the samples composition and chemical state. In the case of photoelectron microscopy the exciting beam is focused into a narrow spot on the sample surface. The sample is then moved in such a way that the spot moves row by row across the sample surface and as a result photoelectrons are emitted from each irradiated spot. By collecting these photoelectrons, it is possible to map the composition or chemical state across the selected sample area (for example 100 x 100 microns area on a 2 x 2 cm sample). Photoelectrons can escape the material only from near the surface and this means that these methods are very surface sensitive, which makes them extremely useful for surface studies. This also means that the surfaces need to be very clean (cleaned with ion bombardment before measurements) and therefore ultra-high vacuum is needed.

Graphene – a One Atom Thick Corrosion Resistant Coating?

Graphene – a novel material, that consists of only a single layer of oriented carbon atoms. This material is hundreds times stronger than steel and conducts heat and electricity with exceptional efficiency. A perfect sheet of graphene could actually be so strong that it could lift even a kitten! But can this one atom thick material also be the thinnest corrosion resistant coating ever made? There have been several papers over the last decade discussing this possibility and this peaked our interest. So we first prepared graphene on larger copper substrates by chemical vapor deposition (CVD). Following Raman spectroscopy and scanning electron microscopy (SEM) studies confirmed, that we had a single layer of high quality graphene, that coated the whole substrate. Now it was time to test how well this single atom thick coating can protect the underlying copper from corrosion – for that we used chemical and electrochemical methods. According to electrochemical tests, graphene actually seemed to slow down the corrosion, but additional high resolution imaging with the scanning electron microscope revealed the terrifying truth!
Graphene had started to delaminate and the areas with exposed copper had suffered severe corrosion, unlike bare copper substrates, that corroded uniformly. This severe type of copper corrosion in the defects of graphene was actually caused by graphene itself because of localized galvanic corrosion. In this galvanic couple the large area of highly conductive graphene served as a cathode and the small area of exposed copper as an anode. As a result the copper was continuously stripped from electrons, causing it to easily react with the corrosive environment. So basically it was clear that graphene may initially seem to be a corrosion resistant barrier, but eventually the graphene coated substrate would suffer much more damage than the uncoated substrate! Also, it is impossible to create a large area graphene that has no defects where chloride ions wouldnt be able to slip through. However, it was also true that if the defects in graphene were to be fixed, the galvanic couple and corrosion would be undone. In our laboratory we sealed these small defects in graphene by electrodeposition of polypyrrole. Surprisingly this polymer deposited extremely well on such defects, sealing even holes that were several microns wide. As a result we obtained a nanocomposite coating, that consisted of graphene and polypyrrole. This coating performed well both in chemical and electrochemical corrosion tests.
So what did we learn from all this? The first thing that we learned was the fact that galvanic corrosion can effectively be stopped even at nano-scale, by blocking one of its driving reactions. Second, we discovered that the electrochemical behavior of the defects of graphene is completely different from the defect free area. Third, we realised that polypyrrole may even visualize the quality of graphene for the naked eye because polypyrrole deposits only on graphene and its defects but not on copper if the defects were too big. For example if one built a CVD (chemical vapour deposition) reactor for the preparation of 1 square meter of graphene on a copper foil, then there is a need to somehow see if the foil was actually evenly coated by graphene. By depositing polypyrrole on the graphene coated copper substrate, it is possible to see even with the naked eye if the whole substrate turns black or of there are brigher areas. If there were brighter areas on this copper foil with graphene and polypyrrole, then this would mean that in those regions we dont actually have graphene where polypyrrole could deposit. This would mean that either the gas flow or temperature in the CVD process had not been ideal.
Although things get complicated in the nano-scaled world, the processes are still governed by a set of rules. One day we’ll figure them all out and then we can truly play „dice“ at the atomic scale!

Template Synthesis of Silver Nanorods

Silver nanorods / nanowires with well defined length (up to tens micrometers) and diameter (around 10 nanometers) can easily be prepared by template synthesis method.

First a template is created by anodizing aluminum. In this process a porous oxide layer is created on top of the metal. The distribution, diameter and length of the pores depends on the anodizing solution and electrical parameters.

In the next step the pores are filled with silver by electrochemical deposition. The growth starts at the bottom of the pores where the pores are connected to the conductive metal. Eventually the whole pore is filled with silver and the deposition is stopped.

In order to get the silver nanorods out of the aluminum oxide matrix, the oxide needs to be etched away. The oxide matrix is removed almost instantly when dipping the substrate into an alkaline solution. As a result the silver nanorods escape into the solution. The amount, diameter and length of the nanorods depends on the oxide template that was used in the preparation process.

Large quantities of silver nanorods can be prepared in that way since in the pores in the oxide matrix are very close to each other which means that after deposition the substrate surface mostly consists of silver in the pores. Also in the etching process only the thin oxide layer is removed from the substrate to extract the nanowires and this means one can easily tune the amount of silver nanorods in a solution by the amount of substrates dipped into the same solution. For example for preparing a solution with a small concentration of silver nanowires only one sample is dipped into the solution. All the nanorods on that sample then go into the solution. By dipping the next sample into the same solution all of the nanowires on the second sample also go into the solution and the concentration is doubled. This process can be repeated as long as aluminium oxide etching is still possible. Note that the sample needs to be removed from the solution once its oxide layer is removed (this may take only a few seconds).

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Atomic Force Microscopy (AFM)

Atomic force microscope (AFM) is a powerful tool that is used to study materials by scanning over the surface with a very sharp tip. When a sharp tip approaches a surface then first Van der Waals attractive forces apply that pull the tip closer to the surface and therefore also bend the cantilever. When the tip is close enough then electrostatic repulsive forces apply. The bending of the cantilever is monitored with a lazer beam that is focused on the cantilever and reflected into the detector.This method allows to obtain greatly magnified high resolution 3D images of the studied substrates (even atomic resolution is possible). The main working modes are contact, non-contact and tapping mode. In then case of contact mode the tip is in direct contact with the material. This is suitable for studying hard surfaces. In the case of non-contact mode the tip is vibrating close to the surface. This mode is used for studying sticky and soft surfaces. In the tapping mode the tip vibrates with a greater amplitude and briefly touches the sample at its lowest point of the trajectory. This method is useful for obtaining a “real” image of the studied surface as the tip penetrates the thin film of water that is always present on substrates when measuring in open air. There are also other types of scanning probe microscopes where different information can be obtained from the sample. For example a if one uses a thermocouple as a sharp tip for scanning then it is possible to study heat distribution on microscopic electronic devices in order to detect possible spots where oveheating occurs. In the case of scanning tunnel microscopy an electric potential is applied between the tip and the sample, which causes the movement of electrons from one to other. By measuring the tunneling current, it is possible to obtain valuable information about the state of the surface. Even atomic resolution is possible in STM and therefore can be used to study novel materials such as graphene. It is also possible to use magnetic needles or thin optical cables as tip for scanning over the studied surface.

How to Renew Tarnished Silver

Silver, a valuable metal, has been used long time in making coins, tableware and jewelery. The metal surface however becomes tarnished within a few years and this is caused by corrosion as silver reacts with the surrounding environment.

The surfaces can be easily renewed with stuff available at home – all you need is water, aluminum foil, salt and soda.

Follow these steps to do it yourself:

1. Mix salt and soda into water

2. Wrap the silver price into aluminum foil

3. Put the wrapped silver piece into the solution and wait a few minutes


For a greater effect you might want to boil the water solution as chemical reactions occur faster at higher temperatures.


Why this simple technique works? Silver is usually tarnished as it forms silver sulfide. In order to remove sulfur from the silver, it is needed to put it into contact with a more active metal such as aluminum. The solution there provides with a path for sulfur to move from silver to aluminum.



How Anodizing Works

Anodizing is an electrochemical process where a thicker oxide layer is grown on the material. This is useful for improving an objects corrosion and wear resistance, manufacture nanoporous templates or give the material a decorative appearance. Not all materials can be anodized however as their oxides are not dense and hard but the technique has been widely used on aluminum, titanium, zinc, magnesium and their alloys.

The anodizing system consists of a power source, anodizing bath, electrolyte and anodizable material. The bath is usually made from a chemically resistant conductive material such as stainless steel and serves as a cathode. The anodizable material serves as an anode and is placed inside the anodizing bath with the electrolyte. Both the anode and the cathode need to be connected to the power source. The grown oxide layers properties depend on the material, used electrolyte, temperature and electrical parameters used for anodizing.

In order to produce a uniform oxide layer, the substrates are also treated before the process. The main problem is usually organic contamination of the surface, which prevents growth of the oxide layer. This is removed with organic solvents such as acetone. Often the thin native oxide layer is also removed via etching before the anodizing.