培倫 asked in 教育與參考考試 · 1 decade ago

製造工程 請高手解答!

1. Identify some materials that have a crystalline structure

2. Define the recrystallization temperature for a metal.

3. Define the specific heat property of a material.

4. What is the mechanism by which carbon strengthens stainless steels?

5. What is clay used in making ceramic products?

6. What is cross-linking in a polymer,and what is its significance?

7. Name the two basic mold types that distinguish casting processes.

Update:

可否用中文簡述之

2 Answers

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  • 1 decade ago
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    1. Identify some materials that have a crystalline structure

    Atoms organize themselves in crystalline structure most of the time. Examples are metals, diamond and other precious stones, ice, graphite.

    2. Define the recrystallization temperature for a metal.

    It is the lowest temperature at which the distorted grain structure of a cold-worked metal is replaced by a new, strain-free grain structure during prolonged annealing. Time, purity of the metal, and prior deformation are important factors for the recrystallization temperature.

    3. Define the specific heat property of a material.

    The specific heat property of any material is the amount of heat required to raise one unit of mass of the material by one degree.

    The most commonly used units for specific heat are kJ/(kg-K), Btu/(lb-F), and cal/(g-K). An important equation relating specific heat,

    Q=M (T2-T1)

    M is mass of the sample. Q is the amount of heat that must be added and T1 and T2 are the initial and final temperatures of the sample.

    4. What is the mechanism by which carbon strengthens stainless steels?

    In general, as the carbon content increases the hardness of the steel also increases.

    Carbon is essential to the formation of cementite (as well as other carbides), and to the formation of pearlite, spheroidite, bainite, and iron-carbon martensite. Martensite is the hardest of the micro-structures. The hardness of steel (or more accurately, the hardenability) is increased by the addition of more carbon, up to about 0.65 percent. Wear resistance can be increased in amounts up to about 1.5 percent. Beyond this amount, increases of carbon reduce toughness and increase brittleness.

    There are three principal types of steel used for toools.

    Low Carbon: Under 0.4 percent

    Medium Carbon: 0.4 - 0.6 percent

    High Carbon: 0.7 - 1.5 percent

    Not sure for Qns 5

    6. What is cross-linking in a polymer,and what is its significance?

    Crosslinking is the joining of a lot of polymer molecules together to form a single supergiant molecule. Polymer molecules are already big(that's why we call them macromolecules). But when we crosslink a sample of a polymer, we join all the polymer molecules together to form a single molecule big enough to see and pick up with your hands.

    By joining all the molecules together you can make a material very, very strong. A lot of things that need to be strong are made of crosslinked polymers. A lot of things that need to be strong are made of crosslinked polymers. For example the airplane parts, the golf clubs, car body panels, bowling balls and etc.

    Most rubber is crosslinked, too. This helps the rubber keep from getting gooey in hot weather and brittle in cold weather.

    7. Name the two basic mold types that distinguish casting processes.

    Green sand casting and air set sand( no bake sand) casting

    Ok~~ Kind of tired~~ I am not sure how detail you want the answer, so I just make it simple to understand. Hope this helps~~

    Source(s): My brain and Internet.
  • 1 decade ago

    1.鑑定有晶體架構的一些材料 2.為一種金屬確定recrystallization溫度。 3.確定一種材料的比熱財產。 4.碳加強不鏽鋼的機製是什麼? 5.黏土被在製造陶器的產品過程中使用什麼? 6.在一個聚合物內的橫向連接是什麼,並且它的意義是什麼? 7.名字區分鑄件過程的兩種基本的霉菌類型。

    2006-03-07 19:45:43 補充:

    1.鑑定有晶體架構的一些材料 原子多數時間在晶體架構組織自己。 例子是金屬,鑽石和其他寶貴的石頭,冰,石墨。

    2.為一種金屬確定recrystallization溫度。 在哪個歪曲的糧食一寒冷工作金屬的架構一新,勞累無糧食架構替換延長退火的是低溫。 時間,金屬的純潔,和早先的變形是recrystallization溫度的重要的原素。

    2006-03-07 19:45:55 補充:

    3.確定一種材料的比熱財產。 任何材料的比熱財產是要求培養材料的一單位群眾一度的熱的數目。 最比熱的通常使用的單位是kJ /(千克K),Btu /(磅因F),以及cal /(g-K)。 一個重要的方程式敘述比熱, Q = M(T2-T1) M 是這個樣品的群眾。 Q是必須被補充說的熱的數量,T1 和T2是這個樣品的最初和最後溫度。

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