WEBVTT - How Is Tungsten So Hard and Heat-Resistant?

0:00:01.890 --> 0:00:07.790
<v Speaker 1>Welcome to BrainStuff, a production of iHeartRadio. Hey BrainStuff, Lauren

0:00:07.810 --> 0:00:13.900
<v Speaker 1>Vogelbaum here. Armor-piercing bullets, rocket engine nozzles, and drill bits

0:00:13.980 --> 0:00:16.759
<v Speaker 1>for cutting through solid rock are just some of the

0:00:16.820 --> 0:00:20.700
<v Speaker 1>products made with tungsten, one of the most heat-resistant elements,

0:00:21.239 --> 0:00:24.380
<v Speaker 1>and when made into tungsten carbide, one of the hardest

0:00:24.579 --> 0:00:30.280
<v Speaker 1>substances in the known universe. Tungsten, like most other metallic elements,

0:00:30.460 --> 0:00:33.410
<v Speaker 1>is almost never found on Earth as a shiny hunk

0:00:33.450 --> 0:00:36.190
<v Speaker 1>of metal. To get a pure piece of it, it

0:00:36.250 --> 0:00:39.050
<v Speaker 1>needs to be chemically isolated from other elements that it

0:00:39.090 --> 0:00:43.430
<v Speaker 1>appears with in compounds, usually the naturally occurring mineral, wolframite.

0:00:44.409 --> 0:00:48.010
<v Speaker 1>That's why tungsten's symbol on the periodic table isn't a T,

0:00:48.330 --> 0:00:51.950
<v Speaker 1>but a W, which is short for wolfram. The name

0:00:51.990 --> 0:00:55.280
<v Speaker 1>tungsten is Swedish for heavy stone, a reference to the

0:00:55.340 --> 0:01:00.150
<v Speaker 1>element's uncanny density and heft. Its atomic number, the number

0:01:00.170 --> 0:01:03.450
<v Speaker 1>of protons in the nucleus of its atom, is 74,

0:01:03.450 --> 0:01:08.410
<v Speaker 1>and its standard atomic weight is 138.84. A pair of

0:01:08.470 --> 0:01:11.630
<v Speaker 1>Spanish chemists and brothers by the name Juan Jose and

0:01:11.690 --> 0:01:15.839
<v Speaker 1>Fausto El Ullar are credited with discovering tungsten back in 1783.

0:01:15.840 --> 0:01:21.040
<v Speaker 1>They were the first to isolate this lustrous grayish-white metal

0:01:21.120 --> 0:01:25.730
<v Speaker 1>from wolframite, which also contains iron and manganese. One of

0:01:25.790 --> 0:01:30.610
<v Speaker 1>tungsten's most impressive and useful properties is its high melting point,

0:01:30.970 --> 0:01:34.800
<v Speaker 1>the highest of all metallic elements. Pure tungsten melts at

0:01:34.819 --> 0:01:37.000
<v Speaker 1>a whopping 6,192 degrees Fahrenheit, that's 3,422 Celsius. And it

0:01:37.020 --> 0:01:39.380
<v Speaker 1>won't boil until it reaches 10,030 degrees Fahrenheit, or 5,555 Celsius,

0:01:39.560 --> 0:01:42.760
<v Speaker 1>which is the same temperature as the photosphere of the sun.

0:01:55.120 --> 0:01:58.500
<v Speaker 1>Just for comparison, even platinum has a melting point of

0:01:58.640 --> 0:02:02.250
<v Speaker 1>just a little over half of tungsten's, a mere 3,215

0:02:02.250 --> 0:02:09.470
<v Speaker 1>degrees Fahrenheit or 1,768 Celsius. Technically, carbon is the only

0:02:09.550 --> 0:02:13.070
<v Speaker 1>element that can get hotter than tungsten without melting. But

0:02:13.210 --> 0:02:16.840
<v Speaker 1>that's sort of cheating because carbon doesn't melt at ambient pressures,

0:02:17.139 --> 0:02:19.639
<v Speaker 1>or rather it sublimes straight from a solid to a

0:02:19.680 --> 0:02:23.119
<v Speaker 1>gas at a bit above tungsten's melting point. at 6,700

0:02:23.120 --> 0:02:30.160
<v Speaker 1>Fahrenheit or 3,700 Celsius. All metals have relatively high melting

0:02:30.240 --> 0:02:34.400
<v Speaker 1>points because their atoms are held together in tight metallic bonds.

0:02:35.419 --> 0:02:39.030
<v Speaker 1>Metallic bonds are so strong because they share electrons across

0:02:39.060 --> 0:02:42.489
<v Speaker 1>an entire three-dimensional array of atoms in a crystal lattice

0:02:42.510 --> 0:02:46.430
<v Speaker 1>structure held together by the electrostatic force of the electrons.

0:02:47.919 --> 0:02:51.500
<v Speaker 1>Tungsten outlasts other metals because of the unusual strength and

0:02:51.520 --> 0:02:56.889
<v Speaker 1>directionality of its metallic bonds. Thomas Edison experimented with lots

0:02:56.910 --> 0:03:01.990
<v Speaker 1>of different filament materials for the incandescent light bulb, including platinum, iridium,

0:03:02.210 --> 0:03:05.970
<v Speaker 1>and bamboo, but it was another American inventor, William Coolidge,

0:03:06.230 --> 0:03:09.370
<v Speaker 1>who's credited with making the tungsten filaments that were used

0:03:09.430 --> 0:03:13.480
<v Speaker 1>in most light bulbs throughout the 20th century. Tungsten is

0:03:13.580 --> 0:03:16.820
<v Speaker 1>useful here because it will emit light, It won't melt

0:03:16.919 --> 0:03:22.200
<v Speaker 1>from the heat, and it's relatively inexpensive. Tungsten's high melting

0:03:22.240 --> 0:03:25.220
<v Speaker 1>point has other advantages, like when it's mixed in as

0:03:25.260 --> 0:03:30.149
<v Speaker 1>an alloy with materials like steel. Tungsten alloys are plated

0:03:30.310 --> 0:03:33.010
<v Speaker 1>onto the sections of rockets and missiles that need to

0:03:33.070 --> 0:03:38.010
<v Speaker 1>withstand tremendous heat, including the engine nozzles that eject explosive

0:03:38.110 --> 0:03:44.060
<v Speaker 1>streams of rocket fuel. Tungsten is also very dense. In

0:03:44.100 --> 0:03:46.730
<v Speaker 1>practical terms, if you held a hunk of tungsten in

0:03:46.810 --> 0:03:49.990
<v Speaker 1>one hand and the same volume of silver or iron

0:03:50.030 --> 0:03:54.770
<v Speaker 1>in the other, the tungsten would feel a lot heavier. Specifically,

0:03:55.030 --> 0:04:00.690
<v Speaker 1>the density of tungsten is 19.3 grams per cubic centimeter. Silver,

0:04:00.750 --> 0:04:04.040
<v Speaker 1>in comparison, is about half as dense at 10.5 grams,

0:04:04.380 --> 0:04:07.780
<v Speaker 1>and iron almost a third as dense at 7.9 grams.

0:04:09.320 --> 0:04:13.940
<v Speaker 1>Tungsten is almost exactly as dense as gold. Counterfeiters figured

0:04:13.970 --> 0:04:16.590
<v Speaker 1>that one out long ago, and sometimes try to pass

0:04:16.750 --> 0:04:22.070
<v Speaker 1>off gold-plated bars of tungsten as pure gold. Of course,

0:04:22.450 --> 0:04:25.190
<v Speaker 1>the density of different elements is a reflection of the

0:04:25.250 --> 0:04:28.490
<v Speaker 1>size of that element's atoms, the number of protons and

0:04:28.550 --> 0:04:32.299
<v Speaker 1>neutrons in the element's nucleus, and the electrons in their orbit,

0:04:33.120 --> 0:04:36.080
<v Speaker 1>meaning that the higher an element's atomic number on the

0:04:36.120 --> 0:04:39.700
<v Speaker 1>periodic table, the larger and heavier its atoms will be.

0:04:41.420 --> 0:04:45.760
<v Speaker 1>Tungsten's high-density heft can be an advantage in certain applications.

0:04:46.380 --> 0:04:50.220
<v Speaker 1>It's often used in armor-piercing bullets, for example, for its

0:04:50.339 --> 0:04:55.060
<v Speaker 1>density and hardness. The military also uses tungsten to make

0:04:55.140 --> 0:04:59.190
<v Speaker 1>so-called kinetic bombardment weapons that shoot a rod of tungsten

0:04:59.230 --> 0:05:02.710
<v Speaker 1>like an airborne battering ram to smash through walls and

0:05:03.029 --> 0:05:07.160
<v Speaker 1>even the armor on tanks. During the Cold War, the

0:05:07.200 --> 0:05:10.760
<v Speaker 1>United States Air Force allegedly experimented with an idea called

0:05:10.980 --> 0:05:14.240
<v Speaker 1>Project Thor that would have dropped a bundle of tungsten

0:05:14.279 --> 0:05:18.580
<v Speaker 1>rods 20 feet long, that's 6 meters, from orbit onto

0:05:18.680 --> 0:05:23.539
<v Speaker 1>enemy targets. These so-called rods from God would have impacted

0:05:23.580 --> 0:05:27.120
<v Speaker 1>with the destructive force of a nuclear weapon, but without

0:05:27.180 --> 0:05:31.760
<v Speaker 1>the nuclear fallout. However … it turns that the cost

0:05:31.860 --> 0:05:34.880
<v Speaker 1>of actually getting such heavy rods into space in the

0:05:34.940 --> 0:05:41.120
<v Speaker 1>first place was prohibitive. Pure tungsten isn't that hard. You

0:05:41.170 --> 0:05:43.890
<v Speaker 1>can cut through it with a handsaw. But when tungsten

0:05:43.970 --> 0:05:48.190
<v Speaker 1>is combined with small amounts of carbon, it becomes tungsten carbide,

0:05:48.589 --> 0:05:52.270
<v Speaker 1>one of the hardest and most wear-resistant substances on Earth.

0:05:53.910 --> 0:05:56.430
<v Speaker 1>For the article this episode is based on, HowStuffWorks spoke

0:05:56.450 --> 0:05:59.790
<v Speaker 1>with John Newsom, a chemist and material scientist via the

0:05:59.850 --> 0:06:04.770
<v Speaker 1>American Chemical Society. He explained, when you put small amounts

0:06:04.830 --> 0:06:08.150
<v Speaker 1>of carbon or other metals into tungsten, it fixes the

0:06:08.190 --> 0:06:14.239
<v Speaker 1>structure and prevents it from being easily deformed. Tungsten carbide

0:06:14.360 --> 0:06:16.860
<v Speaker 1>is so hard, at least a nine on the Mohs

0:06:16.880 --> 0:06:19.620
<v Speaker 1>hardness scale, that it can only be cut by things

0:06:19.720 --> 0:06:24.580
<v Speaker 1>like diamonds or cubic boron nitride. Tungsten carbide is up

0:06:24.600 --> 0:06:27.619
<v Speaker 1>to three times as rigid as steel and can last

0:06:27.660 --> 0:06:30.860
<v Speaker 1>up to 100 times longer than steel under highly abrasive

0:06:30.880 --> 0:06:35.850
<v Speaker 1>conditions and has the greatest compressive strength of all forged metals,

0:06:36.350 --> 0:06:40.570
<v Speaker 1>meaning it won't dent or deform when squeezed under tremendous force.

0:06:41.570 --> 0:06:44.890
<v Speaker 1>It can, however, be brittle and may shatter under some

0:06:44.950 --> 0:06:49.169
<v Speaker 1>types of force. The most common use for tungsten carbide

0:06:49.450 --> 0:06:52.049
<v Speaker 1>and the final destination of most of the mined tungsten

0:06:52.110 --> 0:06:56.410
<v Speaker 1>on the planet is specialized tools, and particularly drill bits.

0:06:57.350 --> 0:07:00.010
<v Speaker 1>Any kind of drill bit for cutting metal or solid

0:07:00.070 --> 0:07:03.669
<v Speaker 1>rock needs to withstand the punishing levels of friction and

0:07:03.850 --> 0:07:09.330
<v Speaker 1>heat produced without dulling or breaking. Only diamond drills are

0:07:09.390 --> 0:07:12.720
<v Speaker 1>harder than tungsten carbide, but they're also much more expensive.

0:07:13.880 --> 0:07:17.740
<v Speaker 1>Tungsten's hardness, density, and heat resistance make it ideal for

0:07:17.780 --> 0:07:22.010
<v Speaker 1>a lot of niche applications. Electron microscopes shoot out a

0:07:22.070 --> 0:07:25.950
<v Speaker 1>stream of electrons from a special emitter tip made from tungsten.

0:07:27.240 --> 0:07:30.360
<v Speaker 1>Most welds between metal and glass are made from tungsten,

0:07:30.660 --> 0:07:33.500
<v Speaker 1>because tungsten expands and contracts at the same rate as

0:07:33.540 --> 0:07:38.100
<v Speaker 1>the most common kind of glass, called borosilicate glass. The

0:07:38.220 --> 0:07:41.400
<v Speaker 1>spikes on snowmobile tracks and the tips of trekking poles

0:07:41.520 --> 0:07:45.870
<v Speaker 1>are made from tungsten alloys. Professional-grade darts are made with tungsten.

0:07:46.890 --> 0:07:50.250
<v Speaker 1>In ballpoint pens, the actual ball is often made from

0:07:50.330 --> 0:07:55.910
<v Speaker 1>tungsten carbide. The jewelry industry also makes rings from tungsten carbide,

0:07:56.250 --> 0:08:01.060
<v Speaker 1>especially rings marketed to men. These pieces are very scratch-resistant,

0:08:01.180 --> 0:08:04.960
<v Speaker 1>which is nice, but as nifty as tungsten carbide is,

0:08:04.980 --> 0:08:08.940
<v Speaker 1>I personally would not recommend wearing something so hard to

0:08:09.020 --> 0:08:13.540
<v Speaker 1>cut around something so delicate as a finger. In case

0:08:13.560 --> 0:08:16.310
<v Speaker 1>of emergency, you want a medical professional to be able

0:08:16.330 --> 0:08:18.910
<v Speaker 1>to cut a ring off easily without causing more harm.

0:08:19.730 --> 0:08:24.450
<v Speaker 1>The term degloving gets thrown around. Further, when tungsten carbide

0:08:24.510 --> 0:08:28.480
<v Speaker 1>does shatter, the pieces are very sharp. If you're going

0:08:28.540 --> 0:08:32.780
<v Speaker 1>for an industrial vibe, both jewelry repair and medical experts

0:08:32.940 --> 0:08:38.110
<v Speaker 1>recommend stainless steel instead. Leave the tungsten carbide for the

0:08:38.500 --> 0:08:47.429
<v Speaker 1>armor-piercing bullets and electron microscopes. Today's episode is based on

0:08:47.450 --> 0:08:52.010
<v Speaker 1>the article, Tungsten's Boiling Point is 10,030 Degrees Fahrenheit and

0:08:52.070 --> 0:08:56.370
<v Speaker 1>Other Crazy Facts on HowStuffWorks.com, written by Dave Ruse. BrainStuff

0:08:56.410 --> 0:08:59.630
<v Speaker 1>is a production of iHeart Podcasts in partnership with HowStuffWorks.com

0:08:59.790 --> 0:09:02.620
<v Speaker 1>and is produced by Tyler Klang. For more shows from

0:09:02.670 --> 0:09:06.540
<v Speaker 1>iHeart Podcasts, visit the iHeart Radio app, Apple Podcasts, or

0:09:06.600 --> 0:09:08.459
<v Speaker 1>wherever you listen to your favorite shows.