Composite magnetic recording medium

A system for glass hard disk substrate treatment, comprising

• an oven comprising a receptacle for a glass hard disk substrate and a heat source;
• a control module coupled to the oven and configured cause the oven to anneal the formed glass hard disk substrate to form an annealed glass hard disk substrate and configured to cause the oven to temper the annealed glass hard disk substrate to form a tempered and annealed glass hard disk substrate;
• and
• a pipe positioned to flow air in an inner circumference of a receptacle capable of holding a columnar stack of disks, such that air flows through the inner circumference of the receptacle and the disks;
• wherein the annealing comprises ramping up the formed glass hard disk substrate to an annealing temperature, maintaining the glass hard disk substrate at the annealing temperature for a first amount of time, and cooling the glass hard disk substrate at a first cooling rate;
• and
• wherein the tempering comprises ramping up the annealed glass hard disk substrate to a tempering temperature, maintaining the glass hard disk substrate at the tempering temperature for a second amount of time, and cooling the glass hard disk substrate at a second cooling rate that is greater than the first cooling rate.