Improve Molybdenum Electrode Characteristics Ⅱ

Molybdenum Electrode Picture

There will introduce how to improved molybdenum electrode characteristics when molybdenum at the sintering and forging.

Firstly, when molybdenum electrodes at the sintering, with the slow-smooth warming and phase heat preservation to minimize the temperature difference between inside and outside of electrode blank to prevent excessive thermal stress caused internal hidden cracks and other defects. Proper holding temperature and time guarantee small and uniform grain structure.

Secondly, when molybdenum electrodes at forging should use muffle furnace with hydrogen pass through which can be precisely controlled heating temperature and heating time. On the other hand, there has hydrogen protection so electrodes blanks will not oxide and to avoid the intrusion of oxygen lead to electrodes oxygen content increases and forging loss. Besides, study the forging process (such as forging temperature and deformation amount) of electrodes impact on product quality. Forging temperature and final forging temperature control can get small and uniform grain, but the final forging temperature too low will cause micro-cracks in molybdenum electrodes internal. Table 3 show at the different forging process, the sample has different performance.

Table 3

  Cogging-down Temperature/℃ Forging Temperature/℃ Final Forging Temperature/℃ Deformation Amount(≥)/% Density (>)/(g/cm3) Grain Number/(mm2) Nondestructive  Test
Sample 1 1320 1300 1100 70 10.18 500 No defect
Sample 2 1320 1250 1050 70 10.18 1500 No defect
Sample 3 1320 1200 1000 70 10.18 2500 No defect
Sample 4 1320 1150 950 70 10.15 2500 Micro-crack

Improving characteristics of molybdenum electrode method summary:
Production of high quality electrodes must have high quality molybdenum powder as raw materials and chose high quality ammonium molybdate as raw material with suitable molybdenum powder production process can obtain molybdenum powder which is low impurity content, particle size and size distribution are more suitable.Using appropriate forging technology, particularly suitable forging temperature, the final forging temperature, deformation and pass is high quality molybdenum electrode production key points.

In a word, sound and effective quality assurance system is the basis for produce high quality electrode.