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+--- موضوع: Facts About Scandium (/Thread-Facts-About-Scandium)
Facts About Scandium - bb36ll - ۱۴۰۰/۱۲/۴ ۰۸:۳۴ صبح
دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
is a silvery metal that is soft and has a density of about three times that of water. Scandium is a transition metal and is also considered a rare earth element due to similar chemical properties (such as difficulty in extracting and in separating from other elements) and existence in the same ores, according to Chemicool.Scandium is the 31st most abundant element on Earth, according to Periodic Table, with about 22 parts per million abundance by weight in Earth's crust, according to Chemicool.
Scandium is scattered thinly and has been found in over 800 minerals. Within these minerals, scandium is found in its oxide form (Sc2O3, also known as scandia or scandium oxide), according to Scandium Mining. There are many commercial uses for scandium even though the cost of scandium is typically high – several thousand dollars per kilogram for scandium oxide and up to a few hundred thousand dollars per kilogram for pure دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
, according to Chemistry Explained.
HistoryRussian chemist Dmitri Mendeleev, inventor of the periodic table, predicted the existence and properties of scandium (which he called "ekaboron" — similar to boron) in 1869, according to the New World Encyclopedia. Lars Fredrick Nilson, a Swedish chemist, when examining the spectra of the minerals euxenite and gadolinite, discovered the element in 1879. The element was named for the Latin word for Scandinavia, "Scandia," due to the minerals in which دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
was at that time found to exist only in the Scandinavian Peninsula, according to Peter van der Krogt, a Dutch historian. Per Teodor Cleve, a Swedish chemist, made the link that the new element discovered by Nilson was the same as the proposed element described by Mendeleev.In the first attempt to isolate scandium, Nilson and his team processed 10 kilograms of euxenite and were able to produce about two grams of scandium oxide. According to the New World Encyclopedia, metallic scandium wasn't produced for the first time until 1937 by Werner Fischer, Karl Brünger, and Hans Grienseisen, German chemists. In 1960, 99 percent pure scandium was produced.
What is a master alloy and how is it different from a traditional alloy? And why is the use of دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
so important in the field of jewelry? We find out in this article.
Most of the alloys in our catalog fall under the definition of master alloy and the question of what exactly is meant by this definition may arise.An alloy is a compound made up of two or more elements, of which at least one is a metal. The characteristics of an alloy such as hardness, strength and even color are generally different from those of the elements that constitute it, for example copper and tin, both relatively soft, form the more resistant bronze.An دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
is a particular type of alloy designed to be added to a pure metal, in our case gold or silver, in order to modify its characteristics. A pre-master alloy is a master alloy from which a fundamental element has been subtracted. In our field, it is generally a master alloy from which silver was stolen for logistical reasons.
Why it is necessary to use a master alloy?
Most دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
s are not suitable for technical applications. Pure gold, for example, is extremely soft; this feature makes it easily workable and is one of the reasons for its success in jewelry, but a jewel made of pure gold would easily bend if treated without too much care and would not have sufficient wear resistance. The same considerations apply to silver. For this reason, pure gold is generally transformed into a gold alloy, according to the standard proportions indicated in twenty-fourths, or carats (K).
Until the Second World War, the most popular alloys were mainly formed by three elements: Gold, Silver and Copper.
With the evolution of technique, jewelry has required increasingly specialized performance from alloys, this has led to the need to study the use of new elements to be added to precious metals, which are able to drastically change their characteristics. So we went from having alloys composed of two or three elements, to new formulations that come to contain even 10, effectively increasing the complexity of the product.
What characteristics can a master alloy act on?Once added to the precious metal, a دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
can affect:
- Color
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Hardness
[size=medium]Perhaps the most important feature, as gold and silver are relatively soft when in their pure state. The hardness is controlled through the دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
s both directly, with the simple addition of alloying elements, and indirectly, making the precious metal capable of undergoing hardening heat treatments.[size=medium]
[size=medium][list]
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Melting temperature
[size=medium]It is another important parameter that in some applications it is useful to be able to control. Suppose we need to weld a joint, to do this we can use a particular alloy, which must melt at a lower temperature than the metal that forms the edges of the joint, in this way we will perform a particular type of welding called brazing.[size=medium]The control of the melting temperature is also important in the case of casting with wax setting of stones, where too high a temperature of the metal could irreparably damage the stones.[size=medium]
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Fluidity
[size=medium]Fluidity is an important factor especially in investment casting applications. It can be described as the ability of a liquid metal to faithfully fill an elaborately shaped pattern, such as a grid or filigree.[size=medium]Generally, the fluidity of precious metals increases as the casting temperature increases, but this can cause some side effects, such as interference between metal and refractory material, or evaporation of low-melting alloy elements. To overcome these problems, some elements, such as silicon, can be inserted in the master alloys for investment casting, which are able to increase the fluidity in the liquid state of the metal. In this article we have talked in detail about the role of silicon in investment casting alloys.[size=medium]
[size=medium]Metalmen distributes a wide range of pure metals for all your application requirements. Pure metals are those metals that have not been alloyed with other metallic elements; commercially دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
s are 99% pure minimum. Some of the metals listed below are available as commercially pure and many can be manufactured to be extremely pure, often 99.999% minimum, referred to as “five nines min.”[size=medium]For example, Aluminum 1100 is considered to be commercially pure aluminum – it is 99% pure minimum. Our high purity aluminum can be manufactured up to 99.999% pure. Please note that we will seek to attain the purity level that you request; for example, 99.9%, 99.99% min. If your application demands pure metals, call us or send us your request for quote (RFQ). Our staff is prepared to work with you to determine the purity or dimensional options available to get you the pure materials that you need. Please note that not all metals can be made in all form at high purities.