non academic paper references

non_academic_paper_references/ASTM_standards/Microindentationtester.org.txt

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+Micro indentation tester
+
+
+Image analysis stuff
+PUMA Microscope - https://hackaday.com/2021/09/09/highly-configurable-open-source-microscope-cooked-up-in-freecad/
+https://www.sciencedirect.com/science/article/pii/S246806722300007X
+Make the damn thing an inverted microscope, for god's sake. I'm so done with irregular samples
+https://hackaday.com/2021/04/26/3d-printed-laser-scanning-confocal-microscope-measures-microns/
+https://hackaday.com/2020/05/05/lego-microscope-does-research/
+Stereo microscope??
+https://hackaday.com/2024/04/09/adjustable-lights-help-peer-inside-chips-with-ir/
+openflexure but bigger - https://hackaday.com/2024/03/10/%ce%bcreprap-taking-reprap-down-to-micrometer-level-manufacturing/
+Electron microscope youtube to watch - https://hackaday.com/2019/02/18/electron-microscopes-are-awesome-everything-you-didnt-know-you-wanted-to-know/
+
+TL;DR a Loadcell for the force and a displacement sensor for the displacement
+
+
+
+
+
+
+DIY Hardness testing using a bouncing ball bearing by Tony Foale (Motochassis)
+https://www.youtube.com/watch?v=oxT8Uqq88xM
+https://www.youtube.com/watch?v=4ghW9RNKiDA
+https://s3-us-west-1.amazonaws.com/hmt-forum/tony_foale_hardness_tester.pdf
+
+
+
+
+
+Michel-Uphoff
+https://www.youtube.com/watch?v=CHMexzeWQD8
+https://www.youtube.com/watch?v=mtxRkP5UavY
+https://www.youtube.com/watch?v=ZBGS0ZLZPTY
+
+
+Accurate precision level
+https://www.youtube.com/watch?v=8F6tnOIg0FA
+https://www.youtube.com/watch?v=dhGLn6MObcE
+
+
+General Infi
+https://xometry.pro/en/articles/hardness-testing-of-metals/
+
+
+
+
+
+LitReview
+https://www.technoarete.org/common_abstract/pdf/IJERCSE/v4/i2/2.pdf
+https://www.mdpi.com/2073-4352/7/10/258
+

non_academic_paper_references/ASTM_standards/friction.org

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+In dry sliding between a given pair of materials under steady conditions, the
+coefficient of friction may be almost constant. This is the basis for two
+EMPIRICAL Laws of Sliding Friction, which are often known as Amontons’ Laws
+and date from 1699. They are in fact not original but a re-discovery of work by
+Leonardo Da Vinci dating from some 200 years earlier.
+Amontons’ Laws of Friction can be stated as follows:
+1. Friction is proportional to normal load.
+2. The friction is independent of the apparent area of contact.
+A third Law of Friction was added by Coulomb (1785):
+3. The friction is independent of sliding velocity.
+These three Laws are collectively known as the Amontons-Coulomb Laws. They
+are based on EMPIRICAL OBSERVATIONS only and there is NO PHYSICAL BASIS
+for these Laws. If a tribological contact does not appear to behave in agreement
+with these Laws, it does not mean that there is something suspect about this
+behaviour. These Laws are not FUNDAMENTAL in the same way that Newton’s
+Laws are fundamental.
+Most metals and many other materials in dry sliding conditions behave in a way
+that broadly agrees with the First Law. Contacts between metals and ceramics
+and metals and polymers rarely agree with the First Law.
+Most materials agree with the Second Law, with the exception of polymers.
+Most materials agree with the Third Law, but only over a moderate range of
+sliding velocities. The transition from rest to sliding at low velocities does not
+agree with the Third Law and at high sliding velocities, in particular in metals,
+the dynamic friction coefficient falls with increasing velocity.
+Further Laws have subsequently been added, until we end with:
+1. Friction is proportional to normal load.
+2. Friction is independent of the apparent area of contact.
+3. Friction is independent of sliding velocity.
+4. Friction is independent of temperature.
+   5. Friction is independent of surface roughness.
+These are, in sum, the classical laws of friction. Ceramics and polymers usually
+do not conform to these laws.
+Modern understanding of friction stems from the work of Philip Bowden and
+David Tabor (mostly at Cambridge) between the 1930s and the 1970s and is
+based on careful analysis of contact mechanics. Their model for sliding friction
+assumes firstly that all frictional effects take place at the level of micro (or
+asperity) contacts and that the total friction force has two components: an
+adhesion force and a deformation or ploughing force. The former is associated
+with the real area of contact at an asperity level, the latter with the force
+needed for the asperities of the harder surface to plough through the softer
+surface. These assumptions are sufficient to explain why many material
+contacts do not behave in accordance with the classical Laws of Friction.
+In a metal-metal contact, the deformation at an asperity level is mostly plastic.
+This means that the real area of contact is proportional to load. Increasing load
+leads to an increase in the number of asperity contacts rather than an increase
+in the average asperity contact surface area; more asperities are brought into
+action to support the increased load. Because of this, there is minimal increase
+in penetration depth of the asperities. As the ploughing component of friction
+depends on penetration depth, it is thus not highly dependent on load. The
+adhesion component however is proportional to the real area of contact, hence
+the load. Hence, the total friction in this type of contact is effectively
+proportional to load. It is of course important to note that even this agreement
+with the Classical Laws breaks down once oxide and other surface films are
+present or once work hardening at an asperity level takes place.
+By comparison with the metal-metal contact, metal-ceramic and metal-polymer
+contacts tend to give rise to elastic deformation at an asperity level. In
+ceramics, this is because of very high hardness. In polymers this is because the
+ratio between Young’s modulus and hardness is low. This means that, except in
+the case of contact between a polymer and a very rough surface, the contact is
+almost completely elastic.
+A further consideration in respect of contacts involving polymers is the strong
+time dependence of their mechanical properties; most polymers are visco-
+elastic.
+In those contacts where the deformation at asperities level is elastic (as
+opposed to plastic) the real area of contact for a single asperity will be
+proportional to the load raised to the power 2/3. The real area of contact thus
+increases by less than proportional to load. Because of this, the friction force
+tends to decrease with increasing load, but this is only true with a relatively
+smooth metal counter face, where adhesion friction predominates.
+Whereas surface roughness does not have much impact on the friction in a
+metal-metal contact other than during running-in processes, this is not the case
+with the metal-polymer contact. Minimum friction is achieved with a metal
+surface roughness of around 0.2 Ra. With higher surface roughness, the
+ploughing contribution to friction increases sharply with increased penetration of
+the polymer surface, whereas with very smooth surfaces the adhesion
+component of friction increases dramatically. Of course, these frictional
+responses will be modified by the presence of either transfer films or entrained
+debris.
+Before leaving the issue of surface roughness, it is worth noting that in addition
+to the bulk effect of surface roughness, asperity orientation and shape also
+have an effect on friction. With a metal surface ground in one direction, the
+frictional response of a polymer sliding across the surface may depend on the
+orientation of the surface topography relative to the direction of sliding. This
+can prove a particular problem in running a polymer pin on the surface of a
+metallic disc in a pin on disc configuration.
+Now, whereas in the metal-metal contact, over a limited speed range, we can
+ignore the effects of sliding velocity, we cannot do the same for the metal-
+polymer contact. This is because of the visco-elastic properties of the polymer:
+the higher the deformation velocity, the higher the effective Young’s modulus of
+the polymer. This results in lower surface penetration at higher speeds and
+hence lower ploughing friction and a lower real area of contact and hence lower
+adhesive friction.
+In our final consideration of the classical Laws of Friction, we should perhaps
+consider temperature. In the metal-metal contact, modest temperatures do not
+give rise to major changes in the mechanical characteristics of the materials, so
+it is perhaps safe (over a modest temperature range) to consider that friction is
+independent of temperature. This is of course no longer the case at elevated
+temperatures or under conditions at which asperity tip temperatures result in
+the softening or melting of the material.
+In the case of polymers, the Young’s modulus falls sharply with rising
+temperature leading to an increase in contact area and an increase in adhesive
+friction. The product of friction and sliding velocity is frictional energy input,
+giving rise to an increasing contact temperature. This is accompanied by a
+further softening of the material and increase in friction, which reaches a
+maximum at the point where the real area of contact approaches the nominal
+area of contact. Further increase in temperature will cause the polymer to melt
+or collapse. This is the PV limit of the material.
+From the above analysis, it should be clear that for many contacts the classical
+Laws of Friction do not apply. A different set of Laws of Friction should perhaps
+be postulated as follows:
+1. Friction is NOT proportional to normal load.
+2. Friction is NOT independent of the apparent area of contact.
+3. Friction is NOT independent of sliding velocity.
+4. Friction is NOT independent of temperature.
+5. Friction is NOT independent of surface roughness.
+Because ceramics and polymers do not obey the classical Laws of Friction,
+because the friction coefficient varies so greatly with load, sliding speed,
+surface roughness and temperature, a list of friction coefficients for such
+materials is of no value. This represents a serious challenge for the
+manufacturers of these materials when attempting to produce data of use in
+engineering design applications.
+And finally, a brief glance at the Stribeck curve should be sufficient to convince
+anyone that the classical laws of dry sliding friction obviously do not apply to
+lubricated contacts!

non_academic_paper_references/ASTM_standards/index.org

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+
+
+
+
+| Rockwell                                              | ASTM E18               |
+| Vickers                                               | ASTM E384              |
+| Adhesion Strength Tensile Test                        | ASTM C633              |
+| Area Percent Porosity                                 | ASTM E2109             |
+| Coating Thickness                                     | ASTM B487              |
+| Metallographic Preparation                            | ASTM E3, E1920         |
+| Grain Size (Comparison Method Only)                   | ASTM E112, E930        |
+| Microetching                                          | ASTM E407              |
+| Alpha Case                                            | MCL III-273            |
+| IGA/IGO / Casting Mold Reaction/Alloy Depletion       | MCL III-251            |
+| Delta Ferrite                                         | MCL III 237.06         |
+| Heat Treatment Solution/Incipient Melting Measurement | MCL III-221            |
+| Wrought Titanium Microstructure                       | MCL III-273            |
+| Micro Porosity by Image Analysis and Point Count      | MCL III-270, ASTM E562 |
+| Oxidation Test                                        | HRC LM-100             |
+
+* Specimen Pairs & Wear
+
+The first issue to address in designing a test is which way round, in terms of relative hardness, to have the specimen pair. Traditionally, many wear tests have involved running a soft pin or ball on a hard disc or plate. Under these conditions, the wear occurs on the softer material, sometimes accompanied by the generation of a transfer film on the harder material.
+
+Measurement of material lost from the softer pin or ball is relatively easy. It should however be remembered that if material has been transferred to the disc or plate, its mass may increase.
+
+If the specimen pairs are reversed, with a harder pin or ball running on a softer disc or plate, we generate a different mechanism, depending on the relative hardness, the contact pressure and contact shape. What happens to the disc or plate specimen depends on the nature of the material.
+With metallic specimens, plastic deformation of the surface and work hardening may take place, thus changing the nature of the material. With coated surfaces, repeated passes by a hardened pin or ball may give rise to adhesion-de-lamination and subsequent failure of the coating.
+If we define wear exclusively as the removal of material, it will be apparent that if the scar generated on the disc or plate specimen involves plastic deformation (material is redistributed but not removed), then it cannot be considered in the true sense as a “wear” scar. With this contact configuration, the processes involved may be more analogous to forming or machining processes. In the case of forming, we would anticipate plastic deformation, and in the case of machining, removal of material by cutting or ploughing action.
+
+In real machines, we frequently find contacting materials of similar hardness, with the result that wear is shared between the two contacting surfaces. The only solution here is to measure the wear on both surfaces, not forgetting that, if the materials are different, the wear rate will still be dependent on which material is used for the pin or ball and which is used for the disc or plate. This is because the energy inputs are different for the two specimens.
+
+* Overlap Parameter
+
+Now let’s move on to the overlap parameter.
+If we have a 10 mm diameter pin running on a 100 mm circumference disc track,
+then in one revolution, a point on the pin experiences 100 mm of sliding.
+However, a similar point on the disc sees only a single pass of the pin, hence a
+sliding distance of just 10 mm. Double the track circumference and the point on
+the pin sees 200 mm sliding per revolution whereas the point on the disc still only
+sees 10 mm.
+Hence, in this example, changing the track diameter has a direct impact on how
+the sliding distance, hence the wear, is shared between the two surfaces. It also
+means that running repeat tests at different track diameters, at the same surface
+speed on the same disc, will generate different wear rates.
+By contrast, with the thrust washer arrangement, the sliding distance for a point
+on either sample has to be the same. This probably makes it a better arrangement
+for testing many materials, unless, of course, we wish deliberately to confine the
+majority of wear to one surface.
+The "overlap parameter" (Czichos) is defined as the ratio of sliding distance for
+"body" divided by sliding distance for "counter body". For the thrust washer this
+is 1, for fretting tests it is close to 1, but for pin on disc tests it is variable, but is
+typically less than 0.05. The overlap parameter also applies for reciprocating
+tests, but here there is not the temptation to use the equivalent of different pin
+on disc track diameters, as one would sensibly keep the stroke the same and
+index the specimen plate sideways to run a fresh wear track.
+
+
+* Specimen Orientation
+Slide 22Specimen Orientation
+Let’s think a bit about specimen orientation.
+If we run a pin on disc machine with the pin loaded onto the disc from above, any
+wear debris generated will tend to accumulate on the surface.
+This will give different behaviour from exactly the same configuration turned
+upside down.
+In this case, the debris will fall off the disc surface, giving different friction and
+wear behaviour.
+

non_academic_paper_references/ASTM_standards/meche_metallurgy.org

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+version https://git-lfs.github.com/spec/v1
+oid sha256:c49a583e546028cc0cdcfd4a9d3dbd057a560497f4c6aeab3ca574ec4100d991
+size 103139

non_academic_paper_references/ASTM_standards/meche_tribology.org

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+:PROPERTIES:
+:ID:       6e35d9c4-787d-4334-9c68-457868bcc91b
+:END:
+#+TITLE: Tribolology
+#+AUTHOR: Vishakh Pradeep Kumar
+#+EMAIL: v.kumar@hw.ac.uk
+
+
+# https://youtube.com/playlist?list=PL9nARBd2NBsYWarjXrv4ZxTUl0Qx0izkF
+
+Thermal spraying is an established industrial method for the surfacing and resurfacing of engineered components. Metals, alloys, metal oxides, metal/ceramic blends, carbides, wires, rods and various composite materials can be deposited on a variety of substrate materials to form unique coating microstructures or near-net-shape components. Thermal spray coatings provide a functional surface to protect or modify the behavior of a substrate material and/or component. A substantial number of the world’s industries utilize thermal spray for many critical applications. 4 Key application functions include restoration and repair; corrosion protection; various forms of wear such as abrasion, erosion and scuff; heat insulation or conduction; oxidation and hot corrosion; electrical conductors or insulators; near-net-shape manufacturing; seals, engineered emissivity; abradable coatings; decorative purposes; and more.
+
+Thermal spraying surfaces and resurfaces engineered components to protect or modify the behaviour of a substrate component. Unique coating microstructures made from blending metals, alloys, oxides, ceramics, carbides, and composites are used to resist wear & corrosion, manage thermal efficiency, and enhance electrical properties, among others.
+
+Thermal spray coatings require a heat/energy source, consumable materials, and gases to propel the consumable as fine molten droplets against the part surface. The droplets strike the part, solidify and adhere, with each layer forming a lamellar "pancake-like" splat structure. The metallurgical properties of the coating are dependent on the thermal and kinetic energy used.
+
+
+* Introduction
+
+SEM and x-ray microanalysis capture magnified images and chemical data from metallographic samples. They work in a high vacuum, using a powerful electron beam to analyze backscattered and secondary electrons for insight.
+A conductive specimen is crucial for directing most electrons to the ground. Image formation relies on collecting scattered signals from the beam-sample interaction.
+
+Backscattered and secondary electrons, the primary signals for imaging, arise within the interaction volume. Backscattered electrons are reflected back after elastic interactions between the electron beam and the sample, while secondary electrons originate from the atoms of the sample. Backscattered electrons come from deeper regions of the sample and increase with higher atomic number while secondary electrons originate from surface regions and are less affected by atomic number.
+
+
+* Sample Preparation for Scanning Electron Microscopy
+SEM delves into surfaces, yet interior details are often more interesting; one must uncover them gently while preserving the sample's essence & structures. Mechanical prep boils down to gradual material removal with abrasives in finer steps until the desired outcome.
+
+For metals & alloys, samples are sectioned by saws and prepared by grinding & polishing. Serrated saw blades cut hard - they take a chunk, but mar the surface. Grinding and polishing smooth the surface step by step to reveal the true undeformed microstructure; etching may follow, depending on imaging needs. For best analysis, a pristine, mirror-like flat surface is imperative.
+
+
+** Sample Labeling
+
+Properly marking the SEM specimen is vital. Use an alphanumeric code, unique and constant from sample selection to final data. Direct labeling is rare, but an indelible marker under a metal specimen suffices. If immediate labeling isn't possible, store in a labeled container. Preserve identity, especially with multiple samples on one stage - it is remarkably hard to distinguish between polished samples.
+
+Quality tools aid small specimen labeling and prep. A sturdy 100-mm glass lens with 5x magnification, fixed to adjustable support, near flexible lights, is handy; one can be found with soldering hands. A smaller 10x lens for closer inspection helps.
+
+** Abrasive Sectioning
+
+Cutting aims for minimal damage to microstructure; the right blade is crucial to avoid burning and heat generation. Abrasive discs with silicon carbide or alumina abrasives in a resin or rubber bond are used for abrasive cutting. Be sure to orient the specimen correctly! Blades should enter coating and exit base to keep the coating compressed; cracks should not be formed (by tension) when one wishes to study failure mechanisms. Lubricate for safe & damage-free cutting; in addition to removing swarf, the right cutting fluid protects from rust.
+
+Blades break, samples crack or burn in abrasive cutting. Here's how to identify causes and rectify them:
+- Chipped or broken blades
+  Sample may have moved during cut, secure sample properly.
+  The cutting force might be too high, reduce cutting force weight.
+- Bluish burnt color on specimen
+  Incorrect cutting fluid, blade, or excessive force.
+  Consult applications guideline for proper blade & cutting fluid.
+
+** Precision Sectioning
+
+Thin saws, rim-pressed with diamond abrasive, equipped with micrometers ensure exact alignment and positioning. Finer abrasives produce less damage but take longer; fine grit diamond blades have particle sizes of 10-20 microns, like 600 grit sandpaper, while medium grit wafering blades have particle sizes of 60-70 microns, akin to 220 grit. Regular dressing keeps these blades cutting their best; metal smeared over the abrasive's cutting edge is removed by a ceramic abrasive in a soft matrix.
+
+** Sample Mounting
+
+Mounting secures samples for grinding in controlled orientation while protecting sample edges. The sample is mounted by casting in a hardenable plastic or be compressing it into a hot plastic.
+
+*** Mounting for small sample (eg. powder)
+Most specimens examined in the SEM are much smaller than the SEM chamber and can usually fit on a Cambridge specimen stub, which is 12 mm in diameter and 3 mm thick.
+The general approach is to make the specimen as small as possible without compromising the appearance of the features of interest and the ability of the microscope to image and analyze these features.
+
+** Grinding & Polishing
+Grinding is performed by abrasive particles bonded in resin or metal matrix - silicon carbide for softer materials, diamond for harder ones. Choose abrasives harder than the material but choose methods carefully, as aggressiveness may erode vital features (eg. alumina coatings). Polishing employs loose abrasives for gentler, superior finish although with slower removal.
+
+
+* COMMENT Operational parameters used to chemically analyze samples in the scanning electron microscope
+Depending on the accelerating voltage of the primary beam,
+the BSE and XRP signals are generated deep (μ ms) below the
+surface of the sample, in contrast to the shallow (nms) genera-
+tion depth of the SE signals.
+
+The BSE topographic images are generally inferior to the high
+quality images provided by the SE.
+3. The ideal specimen surface for the most accurate and precise
+analytical information is flat and highly polished in order
+to reduce surface roughness to no more than 100 nm. This
+requirement is particularly important for x-ray microanalysis.
+Resolution of these problems is dependent on sample preparation.
+4. The deeper generation of the BSE and x-ray photons in the
+sample may create operational problems with the analysis of
+thin films on substrates of particles, rough surfaces, and beam
+sensitive specimens.
+
+Table 9.1. Comparison of the different signals and the range of
+operational voltage and current commonly used in scanning elec-
+tron microscopy and x-ray microanalysis. Kv = voltage, A = beam
+current, SE = secondary electrons, BSE = backscattered electrons,
+EBSD = electron backscattered diffraction, EDS = energy dispersive
+x-ray photon spectroscopy, WDS = wavelength dispersive x-ray pho-
+ton spectroscopy, CL = cathodoluminescence
+| Signal | Operational voltage Kv | Operational current A |
+| SE     | 10eV to 30Kv           | 10pA to 200nA         |
+| BSE    | 500eV to 30Kv          | 100pA to 200nA        |
+| EBSD   | 10Kv to 30Kv           | 1–10nA                |
+| EDS    | 1Kv to 20Kv            | 250pA to 200nA        |
+| WDS    | 1Kv to 20kv            | 10nA to 200nA         |
+| CL     | 2Kv to 20Kv            | 300pA to 1nA          |
+
+The two main variable parameters of the incoming primary
+beam are the acceleration voltage and beam current. In simple
+terms,
+the higher the voltage the faster the electrons move and the further they penetrate into the specimen.
+The higher the beam current, the greater the number of electrons.
+High accelerating voltage is associated with increased resolution, and high beam current is associated with an increase in the signal emitted from the specimen.
+
+The actual voltage and beam current used to examine and analyze a given specimen is very variable and strongly influenced by the following sample parameters:
+
+1. The magnification and spatial resolution needed to obtain the
+appropriate information from the specimen
+2. The type of signals needed from the sample
+3. The voltage and current needed to get this information
+4. The density and conductivity of the sample
+5. The sensitivity of the sample to radiation damage
+
+
+
+Backscattered Electron Imaging: Useful for Distinguishing
+Differences Between Broad Groups of Elements
+Unlike the SE signal, the BSE coefficient (η ) increases nearly
+monotonically with the atomic number of the specimen. For
+example, ten times more of the incident electron beam is back-
+scattered by gold than by carbon. The differences in the BSE
+coefficient form the basis of the qualitative analytical procedure.
+A high-atomic-number inclusion in low-atomic-number material
+gives a strong BSE signal, which can be used to give sufficient
+differential contrast in an image, but can only locate the inclusion.
+
+There are four conditions that should be met in order to make
+full and proper use of this analytical technique:
+1. The best signals come from flat, highly polished, conductive
+samples with no preparation induced surface deformations.
+2. There should be maximal specific localization of high-atomic-
+number elements within the sample.
+3. There should be minimal nonspecific distribution of high-
+atomic-number elements within the sample.
+4. The BSE signal must provide an adequate structural images.
+
+
+
+* COMMENT Sample Cleaning
+
+Once cleaned, the specimen either goes directly into the
+specimen chamber of a scrupulously clean SEM. This is not to
+suggest that this is the only time cleaning occurs; it is a continu-
+ous and repetitive process during sample preparation to remove
+every thing that is not an original and integral part of the sample.
+If a particular preparative procedure contaminates the specimen,
+clean it off before going on to the next task.
+
+It is best to assume that all specimens are to some extent
+contaminated (and so too are our fingers). As a golden rule,
+always wear disposable plastic gloves and use clean metal tools,
+such as forceps or tweezers, when handling specimens, placing
+prepared specimens onto the microscope stage, and removing
+them after examination.
+
+There are two general types of cleaning, non-contact cleaning
+in which there is no physical contact between the cleaning agent
+and the specimen, and contact cleaning in which there is physi-
+cal and chemical contact between the cleaning agent and the
+sample. Ideally we would like only to use non-contact processes
+to ensure that the sample surface is undamaged. For example,
+loosely adherent dust can be removed from a dry specimen by a
+puff of clean air or, better still, a low pressure jet of an inert gas
+such as nitrogen. Most cleaning is achieved using solids, fluids,
+chemicals, or high energy beams that are applied to the sample
+surface by varying degrees of physical contact. These processes
+should not leave any traces of the cleaning materials as this may
+compromise any subsequent chemical analysis.
+
+As a general rule the cleaning process should start by using
+the mildest cleaning agent and the least physical contact. There
+is only one rule; the cleaning process must not damage or modify
+the specimen.
+
+
+The cleaning process must remove mineral and organic oils, grease, and paint together with any traces of inorganic and organic chemicals on the surface.
+One of the principal contaminants on metal samples is carbon and organic carbon compounds derived either from faulty cleaning or the microscope itself.
+
+Mechanical means such as high pressure particle abrasion
+such as sandblasting and lapping procedures that will certainly
+clean the sample but at the expense of surface erosion and
+damage. This approach should not be used as a final stage
+for topographical studies, but is a good preliminary cleaning
+process for preparing specimens for subsequent surface analy-
+sis.
+2. Chemical processes such as powerful detergents, organic
+solvents, reactive acids, and alkalis. This approach can be used
+to clean metal surfaces for imaging in the SEM
+
+For topographic imaging, the surface must be degreased by
+washing in high purity solvents such as acetone, toluene, or
+alcohol, using an ultrasonic cleaner. It is important to use several
+changes of the degreasing agent.
+
+
+Table 10.1. A simple procedure for cleaning a metal surface
+1. Remove adherent dry material with a tooth brush.
+2. Remove oil and grease with a suitable solvent and a soft rag.
+3. Treat metal surface with a suitable acid.
+4. Dip into a boiling solution of ammonia and detergent solution
+and scrub well.
+5. Rinse the metal surface ten times first in tap water and then distilled
+water.
+6. Air dry the metal at ambient temperature.
+
+
+
+
+A more vigorous cleaning of non-porous specimens is achieved
+with an ultrasonic cleaner, in which the high frequency vibrations
+are transferred to the cleaning fluid producing a turbulent pen-
+etrating action. These cleaners are used in conjunction with water
+or solvents to remove contaminating material from crevices and
+small holes. Prolonged exposure to an ultrasonic cleaner may
+damage some softer specimens. A final rinse with methanol helps
+to remove any remaining surface films.
+
+
+Plasma cleaning is a very effective way of removing organic
+contamination before the sample goes into the microscope
+
+
+
+This phenomenon was referred to as charg-
+ing and is a common feature of most secondary electron images of
+non-conducting specimens. This is because the secondary electrons
+are emitted with such low energies, 5–50 eV, that local potentials
+due to charging can have a large effect on the collection of the SE
+signal detector, which typically has a potential of +300 V.
+
+
+
+
+
+Modifying the Microscope by Optimizing the Operating
+Conditions to Reduce Charging
+
+However, specimen charging is a unique phenome-
+non of the SEM and it would be erroneous not to briefly consider
+the changes that may be made to the operation of the microscope
+in order to reduce charging. Some of these changes have already
+been hinted at in the Introduction.
+1. Lowering both the voltage and current of the incident beam
+diminishes charging. This is the first and easiest change to
+make.
+2. Changing the scan speed from slow to TV rate diminishes the
+time the sample is exposed to the incoming beam.
+3. Use the higher energy backscattered electron to image the
+specimen rather than the much lower energy secondary elec-
+trons, which are more readily influenced by both positive and
+negative charging.
+4. Charging may be minimized for a given material by operat-
+ing the microscope at a low voltage, with the E1 selected to
+correspond to the E2 upper crossover point as shown in Table
+11.2 . In the modern SEM, the accelerating voltage easily may
+be changed by small increments of 100 eV or less
+
+
+The E2 values may be determined using the scan square test
+described by Joy and Joy (1996). The uncoated sample is placed
+in the SEM and imaged at ×100 at 3–5 Kev and a TV scan rate.
+The magnification is very quickly increased to ×1,000, maintained
+there for 5 s, and then immediately returned to ×100. The small
+scan area at the center of the screen is then examined.
+
+1. If the scan area is brighter than the background, then the sample
+is charging negatively and the beam energy is greater than E2
+(or less than E1
+).
+2. If the scan area is darker than the background, then the sample
+is charging positively and the beam energy is less than E2 (or
+greater than E1
+).
+Set the SEM at its lowest operating voltage and repeat the scan
+square test. If the sample is charging positively, then E1 < E2
+.
+Carefully increase the voltage and image the sample at the point
+where charging is minimized. If the sample is charging negatively,
+then E1 > E2 and it is not possible to lower the voltage any further,
+the sample should be tilted 45° and the scan square repeated.
+1. When carrying out energy dispersive x-ray microanalysis,
+check that the maximum x-ray photon energy emitted from
+the specimen is equal to the energy of the incident electron
+beam producing the x-rays. This is referred to as the Duana-
+Hunt Limit.
+2. Pre-bombard the sample with an argon beam that traps posi-
+tive ions in porous surfaces, which suppresses the build-up of
+a negative charge.
+
+
+
+* COMMENT Sample Artifacts and Damage
+The sole reason for using a scanning electron microscope is to obtain
+accurate, precise and reproducible information about their structure
+and chemical identity. We seek information either to confirm and
+extend our existing knowledge about an object or investigate a new
+and unknown object. The information we obtain is either in the
+form of a picture (image) or as files of numerical data. We need to
+be able to validate this information because the processes of obtain-
+ing images and data using the SEM are usually very invasive and
+totally alien to the environment in which we and our specimens
+exist. We must be satisfied that the procedures used to obtain infor-
+mation do not damage the object or introduce artifacts.
+Damage is an unexpected and irreversible change in the object and
+can occur before and during microscopy. In many cases, damage is
+very obvious in an image and some examples are shown later in
+this chapter. However, sometimes the damage is less immediately
+obvious.
+Artifacts are perceived structural distortions or misrepresentative
+chemical changes to the original object that arise as a consequence of
+the techniques used in preparing objects for subsequent microscopy
+and analysis. Artifacts are frequently not immediately obvious.
+
+Specific Discipline Journals Containing
+Specimen Preparation Methods
+
+Acta Materials www.elsevier.com/locate/actamat
+Corrosion Science www.elsevier.com/locate/corsci
+Intermetallicswww.elsevier.com/locate/intermet
+Journal of Electronic Materials www.springer.com
+Journal of Materials Research www.mrs.com
+Journal of Materials Science www.springer.com
+Materials Science and Engineering www.elsevier.com/locate/msea
+Metallurgy and Materials www.asm.com
+Metallurgical Transactions www.tms.com
+Powder Metallurgy www.maney.co.uk

non_academic_paper_references/ASTM_standards/porosity.org

@@ -0,0 +1,24 @@
+
+* Porosity in Thermal Spray Coatings
+
+
+Thermal spray coatings are susceptible to the formation of porosity due to a lack of fusion between sprayed particles or the expansion of gases generated during the spray process. The determination of area percent porosity is important to monitor the effect of variable spray parameters and the suitability of a coating for its intended purpose.
+
+
+ASTM E 2109 Test Methods for Determining Area Percentage Porosity in
+Thermal Sprayed Coatings
+These test methods cover the determination of the area percentage porosity of thermal sprayed coatings. Method A is a manual, direct comparison method using seven standard images shown on figures in the standard. These figures depict typical distributions of porosity in thermal spray coatings. Method B is an automated technique requiring the use of a computerized image analyzer. The methods quantify area percentage porosity only on the basis of light reflectivity from a metallo-
+
+
+
+
+
+* Coating Thickness
+ASTM B 487 - Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of a Cross Section
+
+This test method covers measurement of the local thickness of metal and oxide coatings by the microscopical examination of cross sections using an optical microscope.
+Under good conditions, when using an optical microscope, the method is capable of giving an absolute measuring accuracy of 0.8 um.
+
+The measuring device may be a screw (Filar) micrometre ocular or a micrometre eyepiece. An image splitting eyepiece is advantageous for thin coatings on rough substrate layers. The measuring device shall be calibrated at least once before and once after the measurement using a stage micrometre. The magnification should be chosen
+so that the field of view is between 1.5 and 3 the coating thickness.
+For the use of automatic image analysis see Section 18.5.5.

non_academic_paper_references/chemicals_MSDS/GHS_Pictogram/README.txt

@@ -0,0 +1 @@
+Images are from https://unece.org/transport/dangerous-goods/ghs-pictograms