Can diodes be connected in series in order to withstand higher voltages then mentioned on them What is the maximum voltage a diode can withstand?

Yes. this is commonly done. However, performance is better and costs lower if you use the proper diode for production devices. Absolutely NOT. For the same reason that capacitor cannot be added in series to withstand higher voltage. Not all components are made equally Supposed that you have two diodes rated at 100v add them in series makes 200v not quite if one leaks more then the other unequal voltage will results blowing them up. There is a simple solution add a parallel high resistor across each component to equalize the voltage then YES it is possible to add them in series