1 00:00:00,690 --> 00:00:13,689 Although there are a lot of other materials, in this course we are going to study deeply wood and metallic materials. 2 00:00:13,689 --> 00:00:38,060 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. 3 00:00:38,060 --> 00:00:51,060 Apart from this, the ores that are the raw materials of metallic materials are exhausted. 4 00:00:51,060 --> 00:01:02,060 So we need to look for another kinds of materials which can do the same application as metallic materials. 5 00:01:02,060 --> 00:01:21,060 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. 6 00:01:21,060 --> 00:01:31,060 In this unit we are going to study the methylated alloys, its properties, its classification. 7 00:01:31,060 --> 00:01:45,060 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. 8 00:01:45,060 --> 00:02:09,060 As I have said, I want to clarify to you that indeed metallic materials aren't just only pure metals. 9 00:02:09,060 --> 00:02:29,060 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. 10 00:02:29,060 --> 00:02:44,060 are indeed alloys, which are mixtures in which metal is in high proportion, but it's not alone. 11 00:02:44,060 --> 00:02:58,060 It's also with another materials that can be metal or non-metal that we have studied in this lesson. 12 00:02:58,060 --> 00:03:10,060 The composition of the alloy, the metallic materials, are the main reason why we can't change its properties. 13 00:03:10,060 --> 00:03:18,060 And also, other thing that we are going to study in this lesson and is usually called heat treatment. 14 00:03:18,060 --> 00:03:28,229 Well, in general, metals have very good properties. 15 00:03:28,229 --> 00:03:36,229 Mechanical properties of metals can be distility, malleability and tenacious, 16 00:03:36,229 --> 00:03:48,229 that make them very good for structural uses. 17 00:03:48,229 --> 00:04:12,330 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. 18 00:04:12,330 --> 00:04:21,329 Both of them are very good, so some of their uses are connected with these properties. 19 00:04:21,329 --> 00:04:26,329 And its color and its shine are very characteristic. 20 00:04:26,329 --> 00:04:33,329 In some uses they can use these properties. 21 00:04:33,329 --> 00:04:41,329 Apart from these, chemical properties are also important. 22 00:04:41,329 --> 00:04:48,730 not very good because they can react with the oxygen of the atmosphere 23 00:04:48,730 --> 00:04:56,089 sometimes it is the main reason why they 24 00:04:56,790 --> 00:05:09,959 they can grow and you need to change these parts. The classification of 25 00:05:09,959 --> 00:05:21,959 Well, we can have so many classifications, but perhaps this is the most easiest of all of them. 26 00:05:21,959 --> 00:05:31,959 We can have two types of metallic materials. 27 00:05:31,959 --> 00:05:45,959 one ferrous, in which iron is in high proportion, and another non-ferrous, in which we haven't any iron. 28 00:05:45,959 --> 00:06:00,959 Ferries are very important because you can change the properties of steel and cast iron, 29 00:06:00,959 --> 00:06:06,959 changing its chemical composition and also with heat treatment. 30 00:06:06,959 --> 00:06:17,959 So it's very important in our society as its application in so many fields. 31 00:06:17,959 --> 00:06:26,959 For example, we can use in our kitchen or also in our reach. 32 00:06:26,959 --> 00:06:31,959 And it's a very, very important material. 33 00:06:31,959 --> 00:06:48,360 No ferrous can also be classified in heavy and light. It depends if the density is high or low than titanium. 34 00:06:48,360 --> 00:07:02,360 In this lesson we are going to talk and explain the properties of this kind of alloys. 35 00:07:02,360 --> 00:07:14,360 Getting back to ferrous alloys, the difference between steels and cast iron is the percentage of carbon in these alloys. 36 00:07:14,360 --> 00:07:20,360 In steels are less than 2% and in cast iron is more than 2%. 37 00:07:20,360 --> 00:07:40,879 Well, in this slide you can see the difference of ferrous alloys, its properties and also its composition and other things. 38 00:07:40,879 --> 00:07:58,579 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. 39 00:07:58,579 --> 00:08:13,060 it has another another things um in some uses for some application you can use this type of 40 00:08:13,699 --> 00:08:21,620 material but it's not very common because it is easily roughed and it's not very 41 00:08:21,620 --> 00:08:34,740 very good but we can also use a cast iron it's alloy with we have a two between two and five 42 00:08:34,740 --> 00:08:50,309 percent of carbon and it also can be white or gray and you can change its property in using 43 00:08:50,309 --> 00:09:07,649 different heat treatment it's hard but it's also very fragile that well the things that you can do 44 00:09:07,649 --> 00:09:18,590 with cast iron are usually very big ones apart from this you can also have steels steels have 45 00:09:18,590 --> 00:09:31,070 less than 2% of carbon we have a very just only with this kind of steel with a simpler but you 46 00:09:31,070 --> 00:09:39,529 can also add another another metallic or non metallic materials for example you can have 47 00:09:39,529 --> 00:09:53,090 stylin steels if you add more than a 12% of chromium it's made that the corrosion 48 00:09:53,090 --> 00:10:07,490 resistance is higher in other way but the the carbon in the steel give give to 49 00:10:07,490 --> 00:10:20,889 the alloy harness but also fragile so you can balance these two properties 50 00:10:20,889 --> 00:10:31,490 the reason why steels are all so important in our society is because you 51 00:10:31,490 --> 00:10:40,450 can change its properties using heat treatment and to understand what happened in in a heat treatment 52 00:10:41,570 --> 00:10:48,129 we we have to take into consideration that this allow is not homogeneous 53 00:10:49,730 --> 00:10:57,330 that means that in in these employees you have more than one phase for example as you can see 54 00:10:57,330 --> 00:11:05,649 here you have the the the equilibrium diagram and the non-equilibrium diagram in an equilibrium 55 00:11:05,649 --> 00:11:13,409 diagram you you can see that you can have in a steel for example in something that is less than 56 00:11:13,409 --> 00:11:25,169 a two percent of carbon you can have a different elements a ferrita you can also have a a mixture 57 00:11:25,169 --> 00:11:37,250 of ferrita and another intermediary compound which is called cemented and do an effective point 58 00:11:38,289 --> 00:11:47,649 and using this effective point if you do different heat treatment if you cool the steel very quickly 59 00:11:47,649 --> 00:12:03,490 what happens is that the cementite can form. You don't have enough time to form it this time, 60 00:12:03,490 --> 00:12:17,169 so it's something that is frozen, the austenite, that is the other one, and it gives very hard 61 00:12:17,169 --> 00:12:26,230 hardness to the alloy so you can have difference another another thing which is called martensite 62 00:12:26,230 --> 00:12:36,129 and it's it's very fragile but it's very hard so this treatment this heat treatment is the 63 00:12:36,129 --> 00:12:47,129 most characteristic one to steels and is the main reason why in our history steel had so 64 00:12:47,129 --> 00:13:01,269 important role to do for example tools and to do shawms and to win battles in the past. 65 00:13:01,269 --> 00:13:17,970 well for non-ferrous alloys is more important we can define there are two very important 66 00:13:17,970 --> 00:13:30,970 from copper and from aluminium copper is a high density materials and you can add it to 67 00:13:30,970 --> 00:13:42,330 copper different different elements for example if you add a tin then you have brass brass is an 68 00:13:42,330 --> 00:13:54,409 alloy that we usually use a to heat applications and copper is a pure copper is used in electricity 69 00:13:54,409 --> 00:14:05,850 of a conductor and you can also have a thing to do soft wheel and so on so there are different 70 00:14:06,970 --> 00:14:15,929 application in no ferrous alloys aluminium is also important nowadays because it has a very 71 00:14:15,929 --> 00:14:31,889 low density about two grains first for the very very very very light so it's very excuses mainly 72 00:14:31,889 --> 00:14:45,690 in transport industry to do for example flights and ships but it's necessary to add copper or to 73 00:14:45,690 --> 00:14:54,789 add a silicon in order to to do a better aluminium with obviously a good heat 74 00:14:54,789 --> 00:15:04,830 treatment so there are a lot of metallic alloys that we use in nowadays to do 75 00:15:04,830 --> 00:15:10,769 different things it's important for the processes titanium for example is used 76 00:15:10,769 --> 00:15:24,019 to a prosthesis and so on. So there are a lot of non-ferrous alloys. We can also change the 77 00:15:25,860 --> 00:15:36,500 properties of metallic alloys with heat treatments. It consists in heating and cooling 78 00:15:36,500 --> 00:15:48,379 chilling the alloys and in this case as we can as we have already explained we 79 00:15:48,379 --> 00:15:59,120 can we can change the hardness and sometimes other properties and these 80 00:15:59,120 --> 00:16:09,980 heat treatments are for example annealing. It consists in heating but not so much and then 81 00:16:09,980 --> 00:16:26,740 let the alloy that cooling slowly. Quenching is when you heat the alloy and then chilling it very 82 00:16:26,740 --> 00:16:41,139 quickly. It is usually used to ferrous alloy to increase its hardness. Tempering is used 83 00:16:41,139 --> 00:16:55,299 after quenching to reduce the stress in the alloy. You also do homogeneous treatments 84 00:16:55,299 --> 00:17:11,980 which are usually very often to cast iron onto nonferrous alloys, to improve the chemical 85 00:17:11,980 --> 00:17:22,680 properties and properties in general, to do the properties more homogeneous in the part. 86 00:17:22,680 --> 00:17:35,279 We can also have precipitation herning that is very common to alloys of aluminium and 87 00:17:35,279 --> 00:17:43,319 other treatments such as surface treatments which change the properties of the surface 88 00:17:43,319 --> 00:17:55,339 but not in the core of the of the parts so you can also increase the ductility sorry the 89 00:17:55,339 --> 00:18:05,740 ductility now the the mechanical properties to to crash well if you want to to get the 90 00:18:05,740 --> 00:18:13,339 mechanic mechanic mechanic metallic or metallic alloys you knew obviously raw materials but in 91 00:18:13,339 --> 00:18:21,900 nature the raw materials for mechanical laws are usually called or there are one characteristic or 92 00:18:22,539 --> 00:18:30,859 for each metal or for each group of alloys for example to iron you can use magnetic 93 00:18:30,859 --> 00:18:48,859 You can also use another one but it is not a very good idea because the process is very complicated. 94 00:18:48,859 --> 00:19:02,460 To copper, cuprite and chalcopyrite, to lithe galen, to thin blend, to mercuricinar, titan 95 00:19:02,460 --> 00:19:12,799 rutile, alumine bauxite and, it's important, the percentage of this ore in the mineral. 96 00:19:12,799 --> 00:19:25,200 The other part is usually called bargein and you have to increase the percentage of ore 97 00:19:25,200 --> 00:19:30,299 which is usually called lo of one ore. 98 00:19:30,299 --> 00:19:45,619 So if you want to get this metallic you need to do a geological study of the part of the 99 00:19:45,619 --> 00:19:56,039 land and to get this ore from the land in a mine. 100 00:19:56,039 --> 00:20:05,599 mines must be a preparation changes a chemical composition so sometimes you 101 00:20:05,599 --> 00:20:11,819 need to do that to cut innate to change from sulfur to 102 00:20:11,819 --> 00:20:21,119 oxygen or to sulfur to sulfate the most important and some sometimes you need to 103 00:20:21,119 --> 00:20:30,279 to do the change from carbonite to oxidant, that is also important. 104 00:20:30,279 --> 00:20:35,039 In any case, you need to crush it. 105 00:20:35,039 --> 00:20:47,420 And sometimes you can do what is usually called sintering, that is something between the metal 106 00:20:47,420 --> 00:20:51,359 and the mineral. 107 00:20:51,359 --> 00:20:59,880 You can get metals using two different processes. One is called hydrometallurgical, 108 00:20:59,880 --> 00:21:08,700 when the lows are very very low, you have not so many ore in the mineral, but you can also 109 00:21:08,700 --> 00:21:19,980 use a heat to get the metal. A hydrometallurgical process is always the same for all the ores. It 110 00:21:19,980 --> 00:21:29,980 This is very common in copper and also, for example, in uranium or other metallic materials. 111 00:21:29,980 --> 00:21:37,980 You heat the mineral and then irrigate with different solutions. 112 00:21:37,980 --> 00:21:52,980 It can have different acidity and it also have some bacteria that can increase the dissolution. 113 00:21:52,980 --> 00:22:02,980 Then you get dissolutions which are rich in metal, metal ions. 114 00:22:02,980 --> 00:22:12,279 You must clean and concentrate the solution and after that precipitate the metal from the solution. 115 00:22:12,279 --> 00:22:25,579 In the last step you need to purify this metal because usually it is very dirty. 116 00:22:25,579 --> 00:22:35,420 In a pyrometallurgy process you have different stages. 117 00:22:35,420 --> 00:22:43,420 We have chosen the iron to illustrate this process. 118 00:22:43,420 --> 00:22:47,420 So in iron you have mainly two stages. 119 00:22:47,420 --> 00:22:53,420 In the first stage you get iron from the ore. 120 00:22:53,420 --> 00:23:10,420 And to do this you use the blast furnace. It's a very big furnace with half different parts as we can study next. 121 00:23:10,420 --> 00:23:21,420 And after that you change from the pig iron, which has more than 2% of carbon, into steel. 122 00:23:21,420 --> 00:23:35,799 So, you need to burn the excess of carbon and also to increase the quantity of iron 123 00:23:35,799 --> 00:23:46,599 in the alloy and at the end you have different profiles of steel. 124 00:23:46,599 --> 00:23:54,839 This is the process as you can see in the blast furnace you have iron ore and coal and 125 00:23:54,839 --> 00:24:07,099 then sometimes you also add limonite to reduce the fusion point, the temperature to get the 126 00:24:07,099 --> 00:24:09,599 liquid metal. 127 00:24:09,599 --> 00:24:23,640 So in the blast furnace the coal can eliminate the oxygen which is in the iron and at the 128 00:24:23,640 --> 00:24:34,920 end you have what is usually called pig iron, which has more or less 4% of carbon. 129 00:24:34,920 --> 00:24:44,200 you need to increase the quantity of iron and you use a caldo converter. There are different 130 00:24:44,200 --> 00:24:49,160 techniques, you can use a caldo converter but you can also use an electric furnace 131 00:24:49,720 --> 00:25:00,359 and at the end you have the liquid steel. So you convert this liquid steel in this 132 00:25:00,359 --> 00:25:16,200 in this plant into different bars or plane or different profiles nowadays we it's very very 133 00:25:16,200 --> 00:25:29,460 common that we use just only electric furnace and we use the the the iron that so it's a recycling 134 00:25:29,460 --> 00:25:39,619 process. With the irons from different parts that we have collected we can 135 00:25:39,619 --> 00:25:53,299 just only go to electric furnace and recycling this iron or this steel. 136 00:25:53,299 --> 00:26:00,220 So, this is the end of this lesson. I hope it can be useful.