Contacting a company that doesnt have any jobs posted and asking for a job has a low probability for success but sure it can happen and I have myself hired people who have done just that. The reason for the low probability of success is that it becomes a question about timing. For it to actually work the company needs to either have a position open that they have not yet advertised or they need to get a new opening that you are a good fit for in the near future. If this doesnt happen they will most likely not Contact you when something becomes open in the future. Your CV and application will then have some time since it was submitted and they dont know if you are still interested.
Instead of doing this my suggestion would be to make Contact with someone at the company that you are interested in and rather than asking for a job telling them about yourself, mention that you are interested in a career within their area of expertise and ask that person what recomendation they have for you to make that happen. You can ask about what skills that would be required ie what might you need to learn etc.
This makes your Contact a networking Contact that you can continue to keep Active rather than a one time event asking for a position. If they do have a position open that you are a good fit for chances are that they will ask you if you are interested.