Many attempts have been done to keep hot food hot on the plate, I know, I have checked the Main patent offices of the world (USPTO, Europe, Japan, China, etc.) but you can Google "Keeping food hot at the table" or "Plates for keeping food hot" to find out for yourself
One thing is selling hot food and other is keeping food hot once it is served; HotSmart Plates are the answer; we manufacture "Heat Retentive Plates" that remain still hot after 30mins+, they need only one minute preheating time in the microwave oven and can be handled safely with the bare hands by the rim while very hot. If you like hot food you will love HotSmart plates.
Take a couple minutes to see our Website; orders have been coming from all over the USA but few people know about it. Please pass it on.