Surface Condition of W/Mo Crucibles Has a Great Influence on Sapphire Growth

Saphhire

Do you know that the surface condition of molybdenum and tungsten crucible has a great influence on sapphire growth? Let us see the details in the following:

If the surface of the crucible is too rough, the sapphire cannot be released or can only be partially released from the wall of the crucible, which results in cracks and faults in the crystal. Not only that: The crucible itself is also damaged in the process and has to be reworked or replaced earlier than planned.

Our pressed-sintered crucibles made of tungsten or molybdenum has a surface roughness of less than 0.8 µm. The sapphire can be extracted from the crucible without difficulty and without damaging the surface of the crucible. For the sapphire producers, this results in fewer complexes and expensive reworking of the surface of the crucible. The cycles run smoothly and deliver high-quality ingots. And there's another advantage: The smooth surface is less susceptible to corrosion caused by the aggressive melted sapphire. This increases the service life of the reusable tungsten/molybdenum crucibles.

Crucible with Smooth Surface

Do you use molybdenum melting crucibles? We are glad to deliver these crucibles with ultra-smooth surface too. Talk to us!

Ground Molybdenum Rod Or Blank Molybdenum Rod

Molybdenum rod is one of the super start products in Chinatungsten Online. We are to provide different molybdenum rods with the different surface conditions and spcifications.

Molybdenum Rod Specification:

Molybdenum rod is manufactured as random length pieces or cut to customers' desired lengths in diameters ranging from 0.080 inches to 6.00 inches. Please view Molybdenum Rod to see our standard sizes of round bar. Below are most of the standard sizes of our molybdenum rectangular bars. If you do not see the size of molybdenum rod that you require, please feel free to contact us.

Blank Molybdenum Rods

Ground Molybdenum Rods

Molybdenum Rod Surface Conditions:

1. Black Surface - Surface is "as swaged" or "as drawn"; retaining a coating of processing lubricants and oxides.
2. Cleaned - Surface is chemically cleaned to remove all lubricants and oxides.
3. Shiny finish - Surface is lathe shinny or polished.

4. Spray sand surface

Molybdenum Rod Application:
Molybdenum rod is mainly used in drawing thin molybdenum wire, molybdenum electrode and steel-making additives. Meanwhile, molybdenum rod is also widely used in the furnace industry for radiation screens, elements, and sintering trays.

Chinatungsten Online is a professional manufacture and sale in providing molybdenum and tungsten products. If you are in need of any Mo/W products, please feel free to contact us.

Molybdenum Properties

Molybdenum

1. Molybdenum Physical properties

In its pure form, molybdenum is a silvery-grey metal with a Mohs hardness of 5.5. It has a melting point of 2,623 °C (4,753 °F); of the naturally occurring elements, only tantalum, osmium, rhenium, tungsten, and carbon have higher melting points.Weak oxidation of molybdenum starts at 300 °C. It has one of the lowest coefficients of thermal expansion among commercially used metals.The tensile strength of molybdenum wires increases about 3 times, from about 10 to 30 GPa, when their diameter decreases from ~50–100 nm to 10 nm.

2. Molybdenum Compounds and chemistry

Molybdenum is a transition metal with an electronegativity of 2.16 on the Pauling scale and a standard atomic weight of 95.96 g/mol.It does not visibly react with oxygen or water at room temperature, and the bulk oxidation occurs at temperatures above 600 °C, resulting in molybdenum trioxide:

2 Mo + 3 O2 → 2 MoO3

The trioxide is volatile and sublimates at high temperatures. This prevents formation of a continuous protective oxide layer, which would stop the bulk oxidation of metal.Molybdenum has several oxidation states, the most stable being +4 and +6 (bolded in the table). The chemistry and the compounds show more similarity to those of tungsten than that of chromium. An example is the instability of molybdenum(III) and tungsten(III) compounds as compared with the stability of the chromium(III) compounds. The highest oxidation state is common in the molybdenum(VI) oxide (MoO3), whereas the normal sulfur compound is molybdenum disulfide MoS2.

Molybdenum(VI) oxide is soluble in strong alkaline water, forming molybdates (MoO42−). Molybdates are weaker oxidants than chromates, but they show a similar tendency to form complex oxyanions by condensation at lower pH values, such as [Mo7O24]6− and [Mo8O26]4−. Polymolybdates can incorporate other ions into their structure, forming polyoxometalates.The dark-blue phosphorus-containing heteropolymolybdate P[Mo12O40]3− is used for the spectroscopic detection of phosphorus.[16] The broad range of oxidation states of molybdenum is reflected in various molybdenum chlorides:

Molybdenum(II) chloride MoCl2 (yellow solid)

Molybdenum(III) chloride MoCl3 (dark red solid)

Molybdenum(IV) chloride MoCl4 (black solid)

Molybdenum(V) chloride MoCl5 (dark green solid)

Molybdenum(VI) chloride MoCl6 (brown solid)

The structure of the MoCl2 is composed of Mo6Cl84+ clusters with four chloride ions to compensate the charge.

Like chromium and some other transition metals, molybdenum is able to form quadruple bonds, such as in Mo2(CH3COO)4. This compound can be transformed into Mo2Cl84−, which also has a quadruple bond.

The oxidation state 0 is possible with carbon monoxide as ligand, such as in molybdenum hexacarbonyl, Mo(CO)6.

What is CIGS?

 What is CIGS?

Copper Indium Gallium diSelenide (CIGS) technology is regarded by some as the most promising thin-film PV contender to the c-Si due to its high conversion efficiencies, potential cost effectiveness and incrementally improving manufacturability.

In order to stay successful and remain profitable, CIGS manufacturers must further increase the ratio of conversion efficiency to manufacturing cost of their modules. 

The former relies primarily on new technological advances, such as the advanced engineering solutions for the absorber layer, interface adjustment and use of better and purer materials. The latter is intimately related to the improved production throughput and yield, better material utilization and improved logistics.

GIGS Processing

GIGS 

In a typical CIGS device, fabrication starts with the deposition of a sputtered molybdenum (Mo) electrode on a substrate, such as soda-lime glass. The use of Mo as the back electrode has remained unchanged since the inception of the CIGS technology. In fact, molybdenum is one of the few metals that remain relatively inert during the CIGS high-temperature (>500 °C) selenization process. 

Despite the fact that CIGS manufacturing recipes vary significantly between individual module producers, the number of “knobs” available in tuning sputter-deposited Mo electrodes is always quite limited. Recipe differences include sputtering pressure and power, the levels of intentionally added impurities, compositional grading profile, and the number and position of sputtering targets in the coater, etc. All of these variables are crucial in achieving high conductivity, proper electrical matching to the CIGS, good adhesion and long-term stability.

The Mo electrode should be about 400-800 nm thick to achieve 0.2 – 0.5 Ohm/sq sheet resistance. Depending on the CIGS fabrication method, the back electrode represents 7-20% of the manufacturing cost of the complete module. There are a number of strong economical and technological reasons for CIGS companies to outsource the back Mo electrode from a large-scale glass manufacturer.

You can visit the following links for more information about  molybdenum or molybdenum alloy.

Molybdenum: http://www.molybdenum.com.cn/

Molytbdenum Alloy: http://www.molybdenum-alloy.com/