鉛の接着／Joining Lead Blocks Together
238.2 هزار بار بازدید -
4 سال پیش
-
DENJIRO: Today, I’ll show you
DENJIRO: Today, I’ll show you a mysterious phenomenon using these two blocks of metal. Now, how would you join these two blocks together?
BOY: Melt them together? Use glue?
DENJIRO: Let's find out. These two blocks are made of lead. Lead is a comparatively soft metal. We won't be using glue to join them together. Instead, we'll use this vise. We'll place the two blocks together and add pressure with the vise.
But this alone... does not make them stick together. Simply applying pressure won’t do. There's a little trick.
We'll place the blocks together at an angle and apply pressure using the vise. Then we'll put them in a straight line by pushing them down and making them rub against each other. Now, we'll take the blocks off the vise. Lo and behold...
BOY: They’re joined together!
DENJIRO: Interesting, isn't it? Why did these lead blocks stick to each other? Lead is a soft metal, so when the two blocks get pressed together, their surface gets slightly deformed, and the area of contact is increased. But this alone will not join the two blocks together. The surface of lead is covered with an oxide film, which forms due to a chemical reaction with oxygen. This film prevents the two blocks from sticking together.
When the two surfaces rub against one another under pressure, the oxide film breaks. Now, the two blocks can be joined together.
Let's test how strong the bond is by lifting a weight. We have here 15 two-liter bottles of water, which weigh about 30 kg in total. Let's try lifting this.
BOY: Amazing! The lead blocks lifted the bottles!
DENJIRO: As you can see, the two lead blocks are firmly joined together. But if you hit one of the blocks from the side with a hammer...
They break apart very easily. Their bond is strong against a vertical pulling force, but weak against force from the side.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!”
BOY: Melt them together? Use glue?
DENJIRO: Let's find out. These two blocks are made of lead. Lead is a comparatively soft metal. We won't be using glue to join them together. Instead, we'll use this vise. We'll place the two blocks together and add pressure with the vise.
But this alone... does not make them stick together. Simply applying pressure won’t do. There's a little trick.
We'll place the blocks together at an angle and apply pressure using the vise. Then we'll put them in a straight line by pushing them down and making them rub against each other. Now, we'll take the blocks off the vise. Lo and behold...
BOY: They’re joined together!
DENJIRO: Interesting, isn't it? Why did these lead blocks stick to each other? Lead is a soft metal, so when the two blocks get pressed together, their surface gets slightly deformed, and the area of contact is increased. But this alone will not join the two blocks together. The surface of lead is covered with an oxide film, which forms due to a chemical reaction with oxygen. This film prevents the two blocks from sticking together.
When the two surfaces rub against one another under pressure, the oxide film breaks. Now, the two blocks can be joined together.
Let's test how strong the bond is by lifting a weight. We have here 15 two-liter bottles of water, which weigh about 30 kg in total. Let's try lifting this.
BOY: Amazing! The lead blocks lifted the bottles!
DENJIRO: As you can see, the two lead blocks are firmly joined together. But if you hit one of the blocks from the side with a hammer...
They break apart very easily. Their bond is strong against a vertical pulling force, but weak against force from the side.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!”
4 سال پیش
در تاریخ 1399/05/10 منتشر شده
است.
238,237
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