Product Information Molybdenum glass melting electrodes (GME)

Superior Products for Critical Glass Operations

To improve the glass industry’s critical applications in melting, homogenizing, feeding and shaping of glass products, H.C. Starck offers superior products and services:

• Molybdenum Glass Melting Electrodes (GME)
• Mo Sheet and Plate for Tank Reinforcement
• Oxidation Protective Coating
• Tubular Targets for Large Area Coating
• Recycling

H.C. Starck’s molybdenum glass melting electrodes (GME) provide the industry with superior quality and the highest product standards for efficient glass melting and electric boosted melting. The high temperature strength and rigidity of molybdenum electrodes, plus the inherent electrical properties of molybdenum, provide maximum operating efficiency. The exceptional purity level of H.C. Starck's molybdenum electrodes (99.95 % minimum) achieves outstanding resistance to chemical corrosion, degradation and minimizes detrimental glass discoloring.

We offer a variety of electrodes for the most demanding glass melting processes:

• Standard and tapered threads including standard metric threads
• GMEs from 1.25" (32 mm) to 8" (203 mm) in diameter
• Machined or centerless ground surfaces for assurance of concentricity and straightness
• Custom fabricated top mounted electrodes and bi-metallic
• Uniform recrystallized grains for creep resistance
• High purity (99.95 % minimum)
• Bubble free, low carbon electrodes

Molybdenum is the “BEST” Choice

H.C. Starck‘s molybdenum is the “best” choice for electric heating in the glass melting process:

• Excellent strength and stability at temperatures over 2000 °C
• High thermal and electrical conductivity
• Low coefficient of thermal expansion (CTE)
• Resistance to corrosion
• Minimizes detrimental glass discoloring
• Good machinability

Traditional and Premium Electrodes

H.C. Starck offers our high purity molybdenum (Mo) and premium molybdenum-zirconium (MoZrO2) glass melting electrodes. Available coated and uncoated with conventional threads and tapered threads for ease of installation.

Glass Melting Electrode Chemical Characteristics¹⁾

Chemical compositions of molybdenum powders for glass melting electrodes with minimum and maximum limits are as follows:

HIGH PURITY MOLYBDENUM ELECTRODES

Element		Standard
Mo	min.	99.95 %
C	max.	0.005 %
Ca	max.	0.003 %
Cu	max.	0.002 %
Fe	max.	0.005 %
Mg	max.	0.001 %
Mn	max.	0.001 %
Ni	max.	0.0015 %
Sn	max.	0.003 %

Mass fraction in %
1) Information on testing methods available upon request.

PREMIUM MOLYBDENUM ZIRCONIUM ELECTRODES

Element		Standard
Mo (By Difference)	min.	98.50 %
Mg	max.	0.001 %
Mn	max.	0.001 %
Ni	max.	0.002 %
Al	max.	0.002 %
Cu	max.	0.002 %
Pb	max.	0.002 %
Ti	max.	0.002 %
Ca	max.	0.003 %
Si	max.	0.003 %
Sn	max.	0.003 %
C	max.	0.005 %
Fe	max.	0.005 %
Cr	max.	0.005 %
Zr		1.2-1.4 %

Maximum variations from straightness will be 0.030 inch per foot (2.50 mm per meter). Maximum variation in cut lengths will be +1/4“, -0 inch (+6.35 mm, -0 mm).

Special tolerances available upon request.

U.S. and European standard and special threads are available on either or both ends.

GMEs Produced by Powder Metallurgy

H.C. Starck’s glass melting electrodes (GME) are manufactured from pure molybdenum and supplied to customer requirements by forging and machining.

Structure 

Glass melting electrodes will normally be shipped as stress relieved. Material can be supplied in the re-crystallized condition upon request.

Dimensional Tolerances
Diameter		Diameter Variation		Out-of-Round
Inches	mm	Inches	mm	Inches	mm
1 1/4	31.7	+/- 0.015	± .38	0.015	0.38
1 1/2	38.1	+/- 0.015	± .38	0.020	0.51
2	50.8	+/- 0.030	± .76	0.025	0.63
2 1/2	63.5	+/- 0.030	± .76	0.025	0.63
3	76.2	+/- 0.040	± 1.0	0.035	0.89
4	101.6	+/- 0.040	± 1.0	0.050	1.27