This process is usually done as a welding process. As a weld pool is laid down and is still molten the carbide grit is introduced. I know that's not what you asked but I thought I would start with a review of the most common technology. Welding is commonly used because of the low cost, high strength and high durability.
Brazing is usually done in one of two ways. You can tin the steel by applying a layer of braze alloy and then sprinkling the grit in while the braze alloy is still molten. You can create a mixture of braze alloy, flux and carbide grit and apply that. You can apply it cold and heat it. You can heat it and dip a cold part into it.
Personally, for a flat surface I would heat the braze alloy with flux and then sprinkle on the carbide grit while it was still molten. If I were applying grit to the end of the pipe I would take a quantity of braze alloy bits, carbide grit and a large amount of flux. I would stir it up and then heat it. I would dip the pipe into it, stir the mixture and apply it that way. The carbide is going to end up on the bottom of the mixture so you want to take that into account.
You can take braze alloy wire, such as .047 diameter, and pretty readily cut it into bits. We have a couple of automatic wire cutters we use for the stuff we supply.
There are a variety of braze alloys that will satisfy your requirements. AWS BAg–22 and BAg–24 are two of the more common alloys. Any braze alloy with silver in the 40% to 56% range should work. Different suppliers have different names for the alloys but all recognize the American Welding Society number. Okay
The drawback to this is the large amount of silver. These alloys are around $25-$30 a Troy ounce now. The braze alloys are relatively soft alloys and are subject to wear.
These alloys typically operate in a range somewhere between 1200 F and 1500 F.
You can use a solder instead of a braze alloy. Typically the difference between solders and braze alloys is whether the temperature is above or below 800°F. Other temperatures are given but they're all about in this range.
If you use a solder your cost will be much lower, your temperatures will be much lower but it will wear much more rapidly.
You can also do the same thing with materials such as epoxies. These have even greater temperature advantages since the great majority set at room temperatures. This is generally the weakest and least wear resistant method of attachment.
Feel free to contact me if you wish to discuss this further.
Thank you for your reply Tom. Do you think the welding process can be done in a regulated furnace with the flux and metal components placed on the steel surface? Which temperature will then be the best?
I have read your other posts and I'm having a bit of trouble trying to figure out the best way to answer you. In my world, how you do something like this is heavily determined by what you hope to achieve and what you have to work with.
I think of welding as joining two pieces of similar material and brazing as joining two pieces of dissimilar material through the use of the third material.
The welding process I described above isn't really welding by this definition. It just uses welding equipment to melt the metal so you can add the ground up carbide. They also make welding rods for hardfacing. These are rods that have the carbide grit already in them.
If the parts are small, say 6" x 9", you can buy a front opening ceramic kiln with the peep hole. You run it up to 2000 F, open the door, put the part in, close the door and then watch the part through the peep hole. You may be able to find one secondhand for a couple hundred dollars. When the temperature comes back up to 1500 F your part should be done.
The braze alloys I am discussing melt over a range. The one I would recommend melts from 1260 to 1290 F. This is an imperfect process so best practice usually dictates taking the temperature up to around 1340 F. You also need a certain amount of energy, supplied as thermal energy, to affect the phase change from solid to a liquid.
You can buy a belt furnace with an atmosphere which eliminates the need to use flux. You put the parts on one end of the belt and they come out on the other end of the furnace.
From the content and construction of your posts it seems as though you are really bright but without much experience in this area.
This, combined with a lack of information about the end product or the equipment available, makes it hard for me to know how to answer you appropriately.
In addition, hardfacing really isn't my primary area. Primarily my area is brazing carbide to steel for tools such as saw blades, router bits and thousands of odd and strange things.
Were I you I would call my local welding supply and see if they had a salesman who could come out. If you get a good one he or she can certainly explain hardfacing to you as well as giving you a quote on the equipment necessary and a pretty good idea of your cost per part. It might be considerably easier and less expensive than you realize.
If you get a really good one he may be able to help you with brazing as well.
If you compare the world of metal joining to a major university then welding is the football team and brazing is the chess team. We're maybe a little cooler than that but welding is far and away the big dog.
