The time it takes for a molybdenum wire furnace to heat to 1500 degrees Celsius may vary depending on the specific furnace, its power and the initial temperature of the furnace. However, it is generally estimated that a high-temperature furnace capable of reaching 1500 degrees Celsius may take approximately 30 to 60 minutes to warm up from room temperature to the required operating temperature.

It's worth noting that heating times can be affected by factors such as furnace size and insulation, power input, and the specific heating element used. In addition, the initial temperature of the furnace and the ambient conditions of the surrounding environment also affect the heating time.

In order to obtain accurate heating times, it is recommended to refer to the manufacturer's specifications and guidelines for the specific molybdenum furnace being used.

The best gas for molybdenum wire furnaces is usually high purity hydrogen. Because hydrogen is inert and reducing, it is often used in high-temperature furnaces for molybdenum and other refractory metals. When used as a furnace atmosphere, hydrogen helps prevent oxidation and contamination of molybdenum wire at high temperatures.

The use of high-purity hydrogen helps create a clean and controlled atmosphere within the furnace, which is critical to preventing oxides from forming on the molybdenum wire during heating. This is especially important because molybdenum readily oxidizes at high temperatures, and the presence of oxygen or other reactive gases can reduce its performance.

It is important to ensure that the hydrogen used is of high purity to minimize the risk of contamination and maintain the required properties of the molybdenum wire. Additionally, the furnace should be designed to safely handle and control hydrogen flow to ensure safe operation. When using hydrogen or any other gas in a molybdenum furnace, always follow the manufacturer's guidelines and safety recommendations.