Vacuum Coating

Vacuum Coating

  • Abdelkader BOUAZIZ added an answer:
    Any suggestion for rapid cooling of coated wire after passing through molten alloy?

    I am working on coating of different alloys on metallic wire in vacuum condition. I want  rapid cooling of coating with the help of helium /argon gas or electrical driven cooling device . Is anyone of you know about electrical device or any suggestion which can do rapid cooling of the coated wire after passing through molten alloy?  I used Helium/ argon gas for cooling purpose but i did not complete amorphous nature of  coating.

    Abdelkader BOUAZIZ · Univ. Ibn Khaldoun Tiaret

    Dear all;

    please make a simple search on "quenching techniques", than you will find the appropriate one to your situation. Please let me know if this does'nt work. Regards

  • Kiril A Pandelisev added an answer:
    How can one deposit ZnO powder in Vacuum coating unit?

    I want to coat ZnO powder in vacuum coating unit. So please provide me with the necessary parameter and minimum Amps required for coating ZnO films. the ZnO powder temperature is 1975 degree

    Kiril A Pandelisev · Crysta Research Corporation

    Have you tried e-beam evaporation? This will be the first approach for me.

  • Sibasish Dutta added an answer:
    Is it possible to observe Surface Plasmon Resonance due to thin silver film produced by Tollen's reagent ?

    Tollens reagent test produces a thin film of silver. Can we control the thickness of this film sufficiently less(50-80 nm) to produce surface plasmons rather than depending on bulky vacuum coating unit?

    Sibasish Dutta · Tezpur University

    Thank you

  • Prashant Thankey added an answer:
    Which one is better for a UHV (ultra high vacuum) leak sealant - Vacseal or Epoxy glue?
    We have an UHV chamber with base pressure 1xE(-10) mbar. There is a manipulator inside the chamber which contains one SS tube used for liquid nitrogen flow to cool down the sample. Recently we got a leak on that tube, which increases the base pressure up to 1xE(-7)mbar. We have to seal the leak. We are debating whether we should use vacseal or silver Epoxy glue. We know vacseal can degas in UHV chamber for a long time if not cured properly (we have experience using it before). On the other hand, we do not know whether silver epoxy is suitable for this purpose or not, because it is on the liquid nitrogen line. Can anybody suggest a solution?
    Prashant Thankey · Institute for Plasma Research

    The sealants you mentioned can be used for temporary leak sealing purposes. As a permanent solution, I suggest what Vittorio suggested.

  • Sibasish Dutta added an answer:
    What are the chemical methods available for the deposition of silver film of nanometer thickness on glass prism to observe surface plasmon resonance?

    To  deposit silver or gold film of nanometer thickness, we need an expensive Vacuum coating machine. Since such expensive machines cannot be afforded everywhere, how can one deposit silver or gold film of nanometer thickness on a glass prism or glass slides? I mean to say that is there any chemical route available?

    Sibasish Dutta · Tezpur University

    Thank you for your suggestion

  • P. Y. Nabhiraj added an answer:
    Does anyone have experience with materials to avoid in vacuum systems?

    I would like to know what kind of materials should be avoided in sputtering processes. I deposit evacuating the chamber around 10^-6/-5 mbar and at working pressures around 1x10^-3 mbar. By the moment I am considering using new materials to deposit different alloys, and because of that I would like to know what materials could generate outgassing around those values. The vacuum chamber is not intentionally heated and therefore the temperatures used are around 60 ºC.

    P. Y. Nabhiraj · Variable Energy Cyclotron Centre

    You are planning to use those metals that have bad vapour pressures. So there is no way to avoid these materials since you want their alloys. So you need larger pumping system to maintain good vacuum. If you are wanting to study the alloys of certain metals that you have mentioned you need to use them!!!!!.. 

    Only way is to optimize the system. Use small targets and large pumping system. 

  • Mohammad Kooti added an answer:
    Why is oxide incorporated when we do pulsed dc reactive sputtering of Aluminium nitride?
    We are trying to deposit Aluminium nitride using pulsed dc reactive magnetron sputtering with pure Aluminium target. However, when we perform EDS analysis of the sample, we are getting 15-20% atomic weight of oxygen in addition to aluminium and nitrogen. Can this be aluminium oxide? Why do we get high percentage of oxygen content even though we are only supplying Argon and nitrogen to the chamber? What can be done to reduce the oxygen content in the sample?

    In contrast, when we try to deposit Aluminium oxide using pulsed dc reactive magnetron sputtering by supplying oxygen and argon, we do not get any nitrogen content in the sample, as seen by EDS analysis. Does Aluminium have more affinity for oxygen instead of nitrogen? Why is this so?
    Mohammad Kooti · Shahid Chamran University of Ahvaz

    Try passing the N2:Ar mixture through an appropriate oxygen scavenger to get rid of the probable oxygen impurity.

  • Silvan Pretl added an answer:
    What are the best practices for thermal evaporation of organic conductive materials?
    Would anybody share any suggestions and recommendations regarding the thermal evaporation of temperature sensitive organic conductive compounds, e.g. pentacene, for experimental preparation of functional electronic structures (diodes, OFETs etc.)?

    I think this shared knowledge could help a lot of people in the beginnings of their experimentation with this class of insoluble functional organic materials.

    Please share your valuable gained experiences with:
    - thermal evaporation process of organic conductivities deposition,
    - particular heating elements, evaporation sources,
    - issues related to film quality,
    - suitable substrates and their preparation, cleaning.
    Silvan Pretl · University of West Bohemia
    Mr. Abbas: Thank you for your valuable input. I will try to look for some book to get to the heart of this matter.
  • Kobus Venter added an answer:
    E-beam evaporation of zirconium oxide for optical coating?
    Can anyone offer any advice on e-beam evaporation of zirconium oxide? Anecdotally, I’ve been told that it’s very difficult to melt the material ‘evenly’.
    The material I have is supplied in tablet form, ~1cm diameter x 5mm thickness. I was able to melt the material to a reasonable degree, but this required quite a high beam current and small beam diameter.
    Additionally, I had some problems with the material spattering during the melt process.

    I’ve heard that there may be doped ZrO2 available, possibly containing a small fraction of magnesium oxide to improve the melting characteristics, but haven’t seen this myself yet.
    Kobus Venter · Swissoptic AG, Heerbrugg, Switzerland
    ZrO2 does not melt properly and predominantly sublimes causing an uneven material surface with craters etc. ZrO on the other hand, does melt well into a pool of molten material that evaporates stable. The material is usually coated directly from the water cooled copper crucible or from a Mo liner. Index and intrinsic stress can be controlled by optimizing the process parameters such as oxygen partial pressure, rate and substrate temperature. Spitting is normally not a problem given that pure material and proper control parameters are used. Granules are usually better to use as starting material, but if only tablets are available, it can be crushed into smaller pieces. The material is melted in small amounts, layer by layer until the crucible or liner is full. Durable layers can be manufactured at low substrate temperature. The material is however in-homogeneous and of limited value in multilayer AR coatings without using an IAD process to control this aspect.
  • Makaraju Srinivasa Raju added an answer:
    Can we put black material on something kept inside vacuum chamber so to remove the reflection of light when doing spectroscopy?
    I need to keep an aluminium stand inside the vacuum chamber running with a TMP for doing Laser Induced Breakdown Spectroscopy. When I was taking a spectrum a lot of reflection was coming from the Al stand. Is there any black material that is available commercially to coat the stand so that the reflection will be stopped?
    Makaraju Srinivasa Raju · Indian Institute of Space Science and Technology
    Thank you Kris Wolfs
  • Artoni Kevin Ang added an answer:
    How can you quantify cracks or other defects on the surface of a metal thin film?
    Right now I only have microscope images of my films, and I want to quantify how many cracks and buckles develop on my film.
    Artoni Kevin Ang · Ateneo de Manila University
    Thanks for the help everyone.

    Santiago Royo, yes, thats what I'm trying to do now, but I'm currently using Matlab. I might try switching to ImageJ.

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