Talk:Ceramic/Archives/2016

Glasses are not ceramics.

Several parts of the article need to be rewritten to correct this mistake. It is a common error, as ceramics and glasses often have similar properties, but they are almost always considered separate classes of materials. This is the reason why glass-ceramics are so named (otherwise it's tautology) and why so many book titles contain the terms "glasses" and "ceramics".Ezrado (talk) 12:39, 7 April 2016 (UTC)

The term "glass" has different meanings, depending on whether we're talking in a scientific sense or a general one. To the general population, "glass" usually refers to silicate glass, which is known for being hard, transparent, and brittle. In the scientific sense, anything that is melted and then cooled quickly enough is a glass. Even water can become a glass if cooled properly. In a scientific sense, many common things we use everyday are technically glasses, even though the general public doesn't think of them as glass. This includes things like plastics, adhesives, silly putty, candy, and much more.

Another one of those is porcelain. Scientifically, it is technically a glass, but to the general public, it is a ceramic. This is because the scientific definition of glass has radically changed over the past few decades, yet the language has not caught up to this change yet. Since we write for a general audience, we need to keep the language and the organization of these things in a way that most people are expecting to find them in. Most people are expecting to find porcelain or other vitreous ceramics in this article, so this article needs to address them as well.

Not to mention that there are also semi-vitreous ceramics, which are much cheaper to make than porcelain but much more water-resistant than clay ceramics. They are something between glass and ceramic. These are common in everyday items like unglazed tiles or dinnerware such as plates and bowls. Zaereth (talk) 16:53, 7 April 2016 (UTC)

In the field of materials science we normally consider glasses to be a separate class of materials to ceramics, otherwise, like you said, we'd be calling amorphous polymers and metallic glasses ceramics, which is obviously not helpful. To avoid this problem we define ceramics as crystalline, inorganic, nonmetallic solids. This is a good definition. That's not to say that the article should peddle this view, but I feel it should at least mention it and point out the distinction between ceramics in a scientific sense and ceramics as the public understands them.

I would also say that porcelain is a ceramic using this definition, as it's major phase is crystalline. It does have some glassy phase, but it's not the major constituent. If we call it a glass then we should also call steel a ceramic (as it has a small amount of the ceramic phase Fe3C in it.Ezrado (talk) 09:47, 8 April 2016 (UTC)

Isn't this addressed in the section Types of Ceramic Materials which states "A glass is often not understood as a ceramic because of its amorphous (noncrystalline) character" and in the section Noncrystalline ceramics?

From Dodd's Dictionary of Ceramics, "In 1920 the American Ceramic Society extended the scope of the word ceramics to include all the silicate industries, bringing in glass, vitreous enamel and hydraulic cement. The problem today is to provide a definition which is sufficiently broad, without including a whole range of naturally occurring materials such as rocks, ores, and minerals..

Dodd's Dictionary of Ceramics covers the issue of defining ceramics (Appendix A - The Definition of Ceramics) with a world-wide view which may be helpful in this discussion. Other sources would be appreciated for this discussion. Gmcbjames (talk) 17:43, 8 April 2016 (UTC)

Hmmm. When it comes to steel, martensite does indeed behave very much like a ceramic, although this is a homogeneous phase all of its own. The more it separates into a heterogeneous microstructure of ferrite, cementite and ε-carbon (Fe₂₄C), the more it behaves like a metal.

There is a similar problem in defining alloys, and, at the same time clarifying the distinction between them and impure metals or other metallic compounds that do not behave like metals, like many gemstones. The distinctions can't be clarified without mentioning them.

I agree that this article needs a lot of work to clarify the technical differences, but it should also not focus solely on crystallines and totally ignore amorphous materials. That, I believe, would also cause much confusion. Instead, it should make clear that many of the things people call ceramics are in fact, technically, glasses, and it should explain why. I think we should also add semi-vitreous ceramics too, and include them in the explanation of the differences. As Gmcbjames says, it already does a little bit, but I think this needs expanding. My time is usually very limited (this is something I do when I'm on hold), and I'm sort of working on the forge welding article at the moment, but will be happy to come back to this and try to help in the near future. Zaereth (talk) 18:17, 8 April 2016 (UTC)

I took a few minutes to do some checking, and many books do refer to porcelain as a glass. The book Fundamentals of Materials Science says this depends on how vitrified the porcelain was during manufacture, ranging from semi-vitreous to highly vitrified, nearly translucent, dental-grade porcelain. Also, looking through the same book, it does describe glass as being a special type of ceramic. Interesting. Zaereth (talk) 21:54, 8 April 2016 (UTC)

This article has the potential of being too technical for the reader. The relationship of ceramic to glass and glass to ceramic is very technical. While most readers would understand an object is either glass or ceramic based on looking at an object, from a technical perspective this is not the case. From my readings, even the experts differ on the subject of glass/ceramic and frankly most of the expert discussion is too technical for my understanding. So for any changes to the article in regards to this discussion, see Wikipedia:Make technical articles understandable. I agree with Zaereth, the article needs expanding in explaining the similarities as well as the differences between glass and ceramic.

On a side note, discussion on this talk page can be more technical and should a reader of the article wish to know more about the technical relationship between glass and ceramic, this talk page discussion may be helpful. Gmcbjames (talk) 17:25, 9 April 2016 (UTC)

I definitely agree on making technical information accessible to the general reader. I work mostly on technical articles, trying to do just that, from Japanese swordsmithing to Basic fighter maneuvers. I'll see what I can do to help when I get a little more time. Zaereth (talk) 20:20, 9 April 2016 (UTC)

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