Most high grade wolframite
concentrate are stopped producing, then the supply of goods is little in
market, so the price difference getting bigger between wolframite concentrate
and scheelite concentrates. The deal of tungsten spot market is still little,
at present, stockists are reluctant to sell out, and the buyers purchase
carefully, the valuable tungsten ore is almost no price, trading volume is very
very low. More and more tungsten carbide factories suspend and reduce
production, the market demand of tungsten powder gets weaker and weaker, the
price is lack of supporting, and the later period price of medium granular
tungsten carbide powder may fail to 170yuan/kg.
2015年7月30日星期四
2015年7月29日星期三
Long-term weak demand of tungsten, in short term, tungsten market rebound is hopeless
Trading volume
of tungsten spot market is still low, limited by long-term weak demand, nowadays,
the market is totally the buyers’. Many products’ quotations and deals are below
everyone’s expectation, such as tungsten concentrate, APT, tungsten powder, etc.
In short term, tungsten market rebound is hopeless.
Macroscopic news,
China “national book” has come out, can cope with 1.5 times’ financial crisis. Our
crude steel yield drops the first time for recent 20 years, the large-scale recombination
of structure is imperative.
2015年7月9日星期四
Top ten hardest materials in the world
Actually, it’s very hard to say which
material is hardest in the world, it depends on the kind of intensity which we
are talking about- tensile strength, shear ductility, yield strength or
hardness. Because there are many definitions of intensity, this article will
introduce 10 kinds of materials, analyzing their intensities from different
aspects.
10. Diamond
A diamond is a transparent crystal of
tetrahedrally bonded carbon atoms in a covalent network lattice (sp3) that
crystallizes into the diamond lattice which is a variation of the face centered
cubic structure. Diamonds have been adapted for many uses because of the
material's exceptional physical characteristics. Most notable is its extreme
hardness. It’s widely used for drill, abrasive paper, saw, etc., and can be
used for cutting, grinding, polishing, and so on. Even diamond is hardest, intensity
is not the biggest, and it will be pieced when you hit it with hammer.
09. Cobweb
Cobweb is with very high tensile strength,
its bearing tension is higher than steel, and can be pulling much longer. Cobweb
which with the highest intensity comes from Madagascar Caerostris darwini, it
can make one of the biggest spider web in the world.
08. carbon/carbon
composites
There are many kinds of carbon/carbon
composites, and all the materials are with good intensity, for example, tungsten carbide. They can resist huge tension, and
can absorb a large amount of strength before crazing. It is very light, so the
kind of composite can be used for aeroengine, Space Shuttle shell and transcontinental
ballistic missile cone.
07. Osmium
(Os )
Osmium (from Greek osme (ὀσμή) meaning
"smell") is a chemical element with symbol Os and atomic number 76.
It is a hard, brittle, bluish-white transition metal in the platinum group that
is found as a trace element in alloys, mostly in platinum ores. Osmium is the
densest naturally occurring element, with a density of 22.59 g/cm3. Its alloys
with platinum, iridium, and other platinum group metals are employed in
fountain pen nibs, electrical contacts, and other applications where extreme
durability and hardness are needed.
06. Maraging
steel
Maraging steels (a portmanteau of
"martensitic" and "aging") are steels (iron alloys) that
are known for possessing superior strength and toughness without losing
malleability, it can be used in aerospace, die and other aspects. Maraging means
the aging of martensite, hard tissue usually appears in steel.
05. Metallic
glass
Metallic glass is made from palladium microalloy,
its chemical structure can neutralize inherent grass fragility while keeping its
hardness. Low density, and lighter than steel, similar to Al and Ti.
04. Wurtzite
boron nitride
Wurtzite boron nitride has similar
structure with diamond, but diamond is formed by carton which under high
pressure for a certain period, wurtzite boron nitride is formed under high
pressure and high temperature when volcano erupting, its hardness is 18% higher
than diamond’s. Similar to diamond, wurtzite boron nitride is employed in
cutting tool and other areas which extreme hardness is needed.
03. Hexagonal
diamond
Hexagonal diamond is maybe the hardest material
in natural. It is an allotrope of carbon with a hexagonal lattice. In nature,
it forms when meteorites containing graphite strike the Earth. The great heat
and stress of the impact transforms the graphite into diamond, but retains
graphite's hexagonal crystal lattice. Hexagonal diamond’s hardness is 58%
higher than diamond’s.
02. Graphene
Graphene is an allotrope of carbon in the
form of a two-dimensional, atomic-scale, hexagonal lattice in which one atom
forms each vertex. It is about 200 times stronger than steel by weight,
conducts heat and electricity with great efficiency and is nearly transparent.
Researchers have identified the bipolar transistor effect, ballistic transport
of charges and large quantum oscillations in the material.
01. Carbyne polysulfide
Even carbyne polysulfide is just a string
of a single atom, tensile strength of it is double of its precursor – graphene.
tensible rigidity is 3 times of diamond, it’s very stable under room
temperature, it can form a predictable crosslinking with other chains when they
are stored together. Simple structure, but its hardness is 200 times of steel’s.
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