QUENCHING

In materials science, quenching is the rapid cooling of a workpiece to obtain certain material properties. It is a mechanical process in which steel and cast iron alloys are strengthened and hardened. These metals consist of ferrous metals and alloys. This is done by heating the material to a certain temperature, depematerial. This produces a harder material by either surface hardening or through-hardening varying on the rate at which the material is cooled. The material is then often tempered to reduce the brittleness that may increase from the quench hardening process. Items that may be quenched include gears, shafts, and wear blocks.

 

How do deep-sea divers operate??

Since ancient times, man's curiosity has led him to explore the dark, mysterious world of the deep seas. Diving has therefore developed to be an important sport over the years. But how do men stay under water for long periods of time??

The first practical diving apparatus was devised by German scientist, named Augustus Siebe in 1819. it comprised a metal helmet with a shoulder plate attached to a water proof leather jacket. A tube running from the helmet was attached to an air pump. this was the first of major experiments he carried out in trying to perfect a safe method of staying and working under water. In 1830 he designed and developed a complete suit and helmet with air valves. Although many improvements have since been made, Siebe's principles remail in universal use.

 Deep sea divers, such as those who search shipwrecks for treasure, are divided into groups. they are skin divers who wear rubber suits that fit tightly like the skin, and divers known as 'hard hats' who wear havy diving dress.

How do astronauts walk in space??

It appears strange but true that astronauts can walk in space. This is so because in ordinary walking we rest our feet on the surface of the earth and the force of earth's gravity pulls us towards it. But there is nothing in the empty space - neither any surface to walk on nor any gravitational force to pull the feet down onto the ground.

          

Any time an astronaut gets out of a vehicle while in space, it is called a spacewalk. A spacewalk is also called an EVA. EVA stands for extravehicular activity.

The first person to go on a spacewalk was Alexei Leonov. He was from Russia. The first spacewalk was on March 18, 1965. It was 10 minutes long.

Today, astronauts go on spacewalks outside the International Space Station. Spacewalks usually last between five and eight hours, depending on the job. 

The world record for the most spacewalks is held by Russian astronaut Anatoly Solovyev. He has been on 16 spacewalks and spent more than 82 hours outside in space. That's almost 3 ½ days of walking in space!!

when was the first artificial satellite launched??

A satellite is an object which has been placed into orbit by human endeavor. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon.

The world's first artificial satellite, the Sputnik 1, was launched by the Soviet Union in 1957. Since then, thousands of satellites have been launched into orbit around the Earth.

 

History changed on October 4, 1957, when the Soviet Union successfully launched Sputnik I. The world's first artificial satellite was about the size of a beach ball (58 cm or 22.8 inches in diameter), weighed only 83.6 kg. Or 183.9 pounds, and took about 98 minutes to orbit the Earth on its elliptical path. That launch ushered in new political, military, technological, and scientific developments. While the Sputnik launch was a single event, it marked the start of the space age and the U.S.-U.S.S.R space race.

What are Black holes??

A black hole is a region of space time where gravity prevents anything, including light, from escaping. The theory of general relativity predicts that a sufficiently compact mass will deform space time to form a black hole.

Around a black hole there is a mathematically defined surface called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.

When a gigantic star reaches the final stage of its life and is about to go supernova (which normally takes billions of years), it spends all the nuclear fuel by then. So it stops burning and heating up and cannot create the nuclear energy required to feed the star and let it make a pivotal balance to support its own gravitational draw against the intense pressures brewing inside.

Therefore its stability cracks under its own gravity. The radius of the star shrinks to a critical size, called the Schwarzschild radius and it starts to devour anything and everything that comes a bit too close, including light. Gravity does its job and the core of the star caves in and implodes.

 

 The outer shells of the star explode into the space. They may even fall into the already dense black hole making it even heavier and denser. And that’s how you get a stellar mass black hole.

Automatic Transmission

If you have ever driven a car with an automatic transmission, then you know that there are two big differences between an automatic transmission and a manu­al transmission:
There is no clutch pedal in an automatic transmission car.
There is no gear shift in an automatic transmission car. 
Once you put the transmission into drive, everything else is automatic.Both the automatic transmission (plus its torque converter) and a manual transmission (with­ its clutch) accomplish exactly the same thing, but they do it in totally different ways. It turns out that the way an automatic transmission does it is absolutely amazing!

The Worlds Largest Internal Combustion Engine

The world’s biggest engine is the Wartsila-Sulzer RTA96-C. It is a turbo charged two stroke diesel engines and it is the most powerful and efficient low revolution engine in the world today.

The Wartsila-Sulser is manufactured by the Aioi Works in Japan and is part of Japans Diesel United Ltd engine manufacturers.

Below is an 89 foot long 44 foot wide 12 cylinder engine, literally as big as a house! What I find confusing is why they haven't actually built the ship around the engine? How they actually get the 2000 ton engine out of the plant and more over install an engine of this size into a ship makes the mind boggle.