Saltar navegación

Activa JavaScript para disfrutar de los vídeos de la Mediateca.

Metallic materials - Contenido educativo

Ajuste de pantalla

El ajuste de pantalla se aprecia al ver el vídeo en pantalla completa. Elige la presentación que más te guste:

Subido el 7 de mayo de 2019 por Isabel L.

112 visualizaciones

Más información Transcripción

Descargar la transcripción

Although there are a lot of other materials, in this course we are going to study deeply wood and metallic materials. 00:00:00
Metallic was very important in the past and nowadays it is also very important, but it is also true that nowadays we have other materials which are better in its properties and obviously in its environmental properties than metallic. 00:00:13
Apart from this, the ores that are the raw materials of metallic materials are exhausted. 00:00:38
So we need to look for another kinds of materials which can do the same application as metallic materials. 00:00:51
But in any case, metallics are very important nowadays and I think in the near future, in the close future, in the next decade at least. 00:01:02
In this unit we are going to study the methylated alloys, its properties, its classification. 00:01:21
Main uses are, at the end of this lesson, we are going to describe the processes that led us to get this kind of materials. 00:01:31
As I have said, I want to clarify to you that indeed metallic materials aren't just only pure metals. 00:01:45
Just only a few, for example, copper, gold, silver, sand lead, can be just only in pure materials, but most of the metallic materials that we use nowadays aren't pure materials. 00:02:09
are indeed alloys, which are mixtures in which metal is in high proportion, but it's not alone. 00:02:29
It's also with another materials that can be metal or non-metal that we have studied in this lesson. 00:02:44
The composition of the alloy, the metallic materials, are the main reason why we can't change its properties. 00:02:58
And also, other thing that we are going to study in this lesson and is usually called heat treatment. 00:03:10
Well, in general, metals have very good properties. 00:03:18
Mechanical properties of metals can be distility, malleability and tenacious, 00:03:28
that make them very good for structural uses. 00:03:36
But they also have another properties such as high density, they are usually solid at room temperature, they have a good conductivity, electrical conductivity and also heat conductivity. 00:03:48
Both of them are very good, so some of their uses are connected with these properties. 00:04:12
And its color and its shine are very characteristic. 00:04:21
In some uses they can use these properties. 00:04:26
Apart from these, chemical properties are also important. 00:04:33
not very good because they can react with the oxygen of the atmosphere 00:04:41
sometimes it is the main reason why they 00:04:48
they can grow and you need to change these parts. The classification of 00:04:56
Well, we can have so many classifications, but perhaps this is the most easiest of all of them. 00:05:09
We can have two types of metallic materials. 00:05:21
one ferrous, in which iron is in high proportion, and another non-ferrous, in which we haven't any iron. 00:05:31
Ferries are very important because you can change the properties of steel and cast iron, 00:05:45
changing its chemical composition and also with heat treatment. 00:06:00
So it's very important in our society as its application in so many fields. 00:06:06
For example, we can use in our kitchen or also in our reach. 00:06:17
And it's a very, very important material. 00:06:26
No ferrous can also be classified in heavy and light. It depends if the density is high or low than titanium. 00:06:31
In this lesson we are going to talk and explain the properties of this kind of alloys. 00:06:48
Getting back to ferrous alloys, the difference between steels and cast iron is the percentage of carbon in these alloys. 00:07:02
In steels are less than 2% and in cast iron is more than 2%. 00:07:14
Well, in this slide you can see the difference of ferrous alloys, its properties and also its composition and other things. 00:07:20
As I can see, there are three main ferrous alloys. We have iron, which sometimes we can use iron without carbon, but it's not really without carbon. 00:07:40
it has another another things um in some uses for some application you can use this type of 00:07:58
material but it's not very common because it is easily roughed and it's not very 00:08:13
very good but we can also use a cast iron it's alloy with we have a two between two and five 00:08:21
percent of carbon and it also can be white or gray and you can change its property in using 00:08:34
different heat treatment it's hard but it's also very fragile that well the things that you can do 00:08:50
with cast iron are usually very big ones apart from this you can also have steels steels have 00:09:07
less than 2% of carbon we have a very just only with this kind of steel with a simpler but you 00:09:18
can also add another another metallic or non metallic materials for example you can have 00:09:31
stylin steels if you add more than a 12% of chromium it's made that the corrosion 00:09:39
resistance is higher in other way but the the carbon in the steel give give to 00:09:53
the alloy harness but also fragile so you can balance these two properties 00:10:07
the reason why steels are all so important in our society is because you 00:10:20
can change its properties using heat treatment and to understand what happened in in a heat treatment 00:10:31
we we have to take into consideration that this allow is not homogeneous 00:10:41
that means that in in these employees you have more than one phase for example as you can see 00:10:49
here you have the the the equilibrium diagram and the non-equilibrium diagram in an equilibrium 00:10:57
diagram you you can see that you can have in a steel for example in something that is less than 00:11:05
a two percent of carbon you can have a different elements a ferrita you can also have a a mixture 00:11:13
of ferrita and another intermediary compound which is called cemented and do an effective point 00:11:25
and using this effective point if you do different heat treatment if you cool the steel very quickly 00:11:38
what happens is that the cementite can form. You don't have enough time to form it this time, 00:11:47
so it's something that is frozen, the austenite, that is the other one, and it gives very hard 00:12:03
hardness to the alloy so you can have difference another another thing which is called martensite 00:12:17
and it's it's very fragile but it's very hard so this treatment this heat treatment is the 00:12:26
most characteristic one to steels and is the main reason why in our history steel had so 00:12:36
important role to do for example tools and to do shawms and to win battles in the past. 00:12:47
well for non-ferrous alloys is more important we can define there are two very important 00:13:01
from copper and from aluminium copper is a high density materials and you can add it to 00:13:17
copper different different elements for example if you add a tin then you have brass brass is an 00:13:30
alloy that we usually use a to heat applications and copper is a pure copper is used in electricity 00:13:42
of a conductor and you can also have a thing to do soft wheel and so on so there are different 00:13:54
application in no ferrous alloys aluminium is also important nowadays because it has a very 00:14:06
low density about two grains first for the very very very very light so it's very excuses mainly 00:14:15
in transport industry to do for example flights and ships but it's necessary to add copper or to 00:14:31
add a silicon in order to to do a better aluminium with obviously a good heat 00:14:45
treatment so there are a lot of metallic alloys that we use in nowadays to do 00:14:54
different things it's important for the processes titanium for example is used 00:15:04
to a prosthesis and so on. So there are a lot of non-ferrous alloys. We can also change the 00:15:10
properties of metallic alloys with heat treatments. It consists in heating and cooling 00:15:25
chilling the alloys and in this case as we can as we have already explained we 00:15:36
can we can change the hardness and sometimes other properties and these 00:15:48
heat treatments are for example annealing. It consists in heating but not so much and then 00:15:59
let the alloy that cooling slowly. Quenching is when you heat the alloy and then chilling it very 00:16:09
quickly. It is usually used to ferrous alloy to increase its hardness. Tempering is used 00:16:26
after quenching to reduce the stress in the alloy. You also do homogeneous treatments 00:16:41
which are usually very often to cast iron onto nonferrous alloys, to improve the chemical 00:16:55
properties and properties in general, to do the properties more homogeneous in the part. 00:17:11
We can also have precipitation herning that is very common to alloys of aluminium and 00:17:22
other treatments such as surface treatments which change the properties of the surface 00:17:35
but not in the core of the of the parts so you can also increase the ductility sorry the 00:17:43
ductility now the the mechanical properties to to crash well if you want to to get the 00:17:55
mechanic mechanic mechanic metallic or metallic alloys you knew obviously raw materials but in 00:18:05
nature the raw materials for mechanical laws are usually called or there are one characteristic or 00:18:13
for each metal or for each group of alloys for example to iron you can use magnetic 00:18:22
You can also use another one but it is not a very good idea because the process is very complicated. 00:18:30
To copper, cuprite and chalcopyrite, to lithe galen, to thin blend, to mercuricinar, titan 00:18:48
rutile, alumine bauxite and, it's important, the percentage of this ore in the mineral. 00:19:02
The other part is usually called bargein and you have to increase the percentage of ore 00:19:12
which is usually called lo of one ore. 00:19:25
So if you want to get this metallic you need to do a geological study of the part of the 00:19:30
land and to get this ore from the land in a mine. 00:19:45
mines must be a preparation changes a chemical composition so sometimes you 00:19:56
need to do that to cut innate to change from sulfur to 00:20:05
oxygen or to sulfur to sulfate the most important and some sometimes you need to 00:20:11
to do the change from carbonite to oxidant, that is also important. 00:20:21
In any case, you need to crush it. 00:20:30
And sometimes you can do what is usually called sintering, that is something between the metal 00:20:35
and the mineral. 00:20:47
You can get metals using two different processes. One is called hydrometallurgical, 00:20:51
when the lows are very very low, you have not so many ore in the mineral, but you can also 00:20:59
use a heat to get the metal. A hydrometallurgical process is always the same for all the ores. It 00:21:08
This is very common in copper and also, for example, in uranium or other metallic materials. 00:21:19
You heat the mineral and then irrigate with different solutions. 00:21:29
It can have different acidity and it also have some bacteria that can increase the dissolution. 00:21:37
Then you get dissolutions which are rich in metal, metal ions. 00:21:52
You must clean and concentrate the solution and after that precipitate the metal from the solution. 00:22:02
In the last step you need to purify this metal because usually it is very dirty. 00:22:12
In a pyrometallurgy process you have different stages. 00:22:25
We have chosen the iron to illustrate this process. 00:22:35
So in iron you have mainly two stages. 00:22:43
In the first stage you get iron from the ore. 00:22:47
And to do this you use the blast furnace. It's a very big furnace with half different parts as we can study next. 00:22:53
And after that you change from the pig iron, which has more than 2% of carbon, into steel. 00:23:10
So, you need to burn the excess of carbon and also to increase the quantity of iron 00:23:21
in the alloy and at the end you have different profiles of steel. 00:23:35
This is the process as you can see in the blast furnace you have iron ore and coal and 00:23:46
then sometimes you also add limonite to reduce the fusion point, the temperature to get the 00:23:54
liquid metal. 00:24:07
So in the blast furnace the coal can eliminate the oxygen which is in the iron and at the 00:24:09
end you have what is usually called pig iron, which has more or less 4% of carbon. 00:24:23
you need to increase the quantity of iron and you use a caldo converter. There are different 00:24:34
techniques, you can use a caldo converter but you can also use an electric furnace 00:24:44
and at the end you have the liquid steel. So you convert this liquid steel in this 00:24:49
in this plant into different bars or plane or different profiles nowadays we it's very very 00:25:00
common that we use just only electric furnace and we use the the the iron that so it's a recycling 00:25:16
process. With the irons from different parts that we have collected we can 00:25:29
just only go to electric furnace and recycling this iron or this steel. 00:25:39
So, this is the end of this lesson. I hope it can be useful. 00:25:53
Autor/es:
Isabel Lafuente
Subido por:
Isabel L.
Licencia:
Reconocimiento - No comercial
Visualizaciones:
112
Fecha:
7 de mayo de 2019 - 23:05
Visibilidad:
Público
Centro:
IES JAIME FERRAN
Duración:
26′ 01″
Relación de aspecto:
4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
Resolución:
1440x1080 píxeles
Tamaño:
352.06 MBytes

Del mismo autor…

Ver más del mismo autor

EducaMadrid, Plataforma Educativa de la Comunidad de Madrid

Plataforma Educativa EducaMadrid