DE1796215B2 - POWDERED BORING AGENT FOR STEEL OR IRON MATERIALS - Google Patents

Description

shaped means achieving technically useful According to a preferred embodiment of the

Barable layer thicknesses with shorter annealing times and / or the invention is the boronizing agent that is used for

make low annealing temperatures possible. Boriding of steel or iron materials

According to the invention, the object is suitably made from 75 to 85 percent by weight,

formation of a group of compounds as Aktivato- 5 preferably 79 percent by weight boron carbide, 10 to

Ren solved, by which the above-described 20 percent by weight, preferably 16 percent by weight

Disadvantages can be eliminated. In the case of the percent borax, and 1 to 10 percent by weight,

according to the invention proposed group of compound 5 weight percent fluoroborate as active

fertilize the powdered boronating agents as a vator.

Activators are to be added, it is io By the inventive use of the

to fluoroborates or boron fluorides. Fluoroborates as activators in powder form

The use of fluoroborates is admittedly from boriene agents can be found in all previously known

boronization in the liquid phase, e.g. B. in salt processes (those with powdered Borienmittel

bathing, known, but the behavior is working) the layer thickness compared to the layer

and the mode of action of the fluoroborates in these 15 thick ones, which can be achieved with non-activated boron agents

Procedure completely different. In the case of boronization in salt, increase considerably; on the other hand it is possible

baths, the latter consist of salts or salt mixtures - an equally thick boride layer is considerably shorter

see the be ^: the proposed treatment time or at a lower boriding temperature to be generated

tcmperatur are liquid and in which elemental boron gene. The activators according to the invention, d. H. the

can be dissolved or dispersed. In the case of the salt, ₂₀ fluoroborates, result in powdery boriene agents

which in the molten state as a solvent - also a stronger activation than previously known -

tel serves for elemental boron, it can become example activators such. B. ammonium chloride,

v / also be fluoroborates. Apart from the effect of the activator, it depends on the

depends on the fundamental differences between the two boronizing agents. As stated now

the procedures, d. H. boronization with molten salt, the effect is strongest in

zen in which boron is dissolved, and boronation with ferroboron and boron carbide-borax mixtures, while

Powder-like boronizing agents, which they have now invented with amorphous boron and mixtures, the amorphous

according to fluoroborates added as activators contain boron, less strongly but still better

is also the mode of action that is known as activators.

Fluoroborates in the bridal _L. mannten procedures 30 In principle, the most varied

completely different. For example, using fluoroborates has an effect. However, it has been shown

in the case of using the fluoroborates as that alkali fluoroborates such as sodium fluoroborate,

Solvents whose high rate of disintegration is NaBF ₄ , or potassium _{fluoroborate, KBF 4} , and ammonia

very annoying. When boriding with powdered nium fluoroborate, (NH ₄ ) BF ₄ , are more suitable than

However, as has now been found 35 Erialkali- and heavy-metal fluoroborates are used for boronating agents.

was just the rapid disintegration of the fluoroborates, The following Ausführungsbe> ^c piel used to weite-

which they valuable as activators for this process Ren explanation of the invention,

power. In this way of working it happens. .

crucial to the fact that the reaction is as exemplary as possible

is set in motion quickly. The use of the 40 for comparison purposes was initially the borie

Fluoroborates as activators for powdery ing of a steel with a low carbon content in

Boriding agent is therefore to be regarded as a completely new type of mixture of 84 percent by weight boron carbide,

and, as clearly shown below, leads to B ₄ C, and 16 percent by weight of borax, Na ₂ B ₄ O ₇ ,

will be carried out to considerable, unpredictable ways. If a workpiece is made, for example

Advantages. 45 steel, in this non-activated mixture for 6 hours

The invention now relates to a powdery treated at 1000 ° C, the result is a very irregular

Boronizing agent for steel or iron materials, moderate layer with a thickness between 0.0ö0 and

standing from ferroboron, amorphous boron, boron carbide varies 0.180 mm.

and / or borax individually or as a mixture, which was then carried out by another boron

characterized in that the boronizing agent 50 is taken with the same workpiece made of steel

Contains fluoroborates as activators. also in a mixture of boron carbide and

The boriding agent activated with fluoroborates, borax, which, however, had been treated with potassium fluoroborate as an extender aluminum oxide, was treated. The activated contained, whereby a caking of the powder boriding agent had a composition of 79 Ge should be prevented. 55 percent by weight B ₄ C, 16 percent by weight Na ₂ B ₄ O ₇ and

The activators present in the boronating agent contain 5 percent by weight of KBF ₄ . Among the same

preferably consist of sodium, potassium or treatment conditions as indicated above,

Ammonium fluoroborate. formed a regular, 0.240 mm thick

The activator is in a layer in the borating agent.

Amounts from 1 to 10 percent by weight, preferably 60. With the help of the invention, the borie

5 percent by weight (based on the boronization with powdered boron agents a considerable amount

medium included. and achieve unpredictable improvement.

Claims (5)

1 2 there are three possibilities, namely boriding in patent claims: molten salt with and without electrolysis and in aqueous solutions with high-frequency heating. 1. Powder boronizing agent for steel The first two processes are very economical or ferrous materials, consisting of ferroboron, but their applicability is made by entamorphism Boron, boron carbide and / or borax form an enamel layer that is difficult to wash off zein or in a mixture, marked by this on the workpiece, marked by the unsatisfactory temperature, that the boronating agent can be regulated by fluorine temperature through corrosion of the crucible borates contains as activators. materials and through the shadow effect (for users 2. Powdered borating agent according to the aniode of the electrolysis) impaired. The third spoke 1, characterized in that the process, namely boriding in an aqueous solvent borating agent In turn, aluminum oxide as an extender has no practical significance. obtained, because because of the reactivity of many boron compounds 3. Powdered boronizing agent according to fertilization with water for this method of operation only borax spoke 1 and 2, characterized in that the 15 and boric anhydride come into question, but with this activator of sodium, potassium or ammo compounds no boron potential he? ^; ,: It werr> n :: nfluorobon: t exists. the one that was capable of diffusing in 4. Borating agent according to spoke 1 to 3, corresponding amount of boron in the surface is sufficient; as a result characterized in that the activator in which it does not come to the formation of a solid Quantities of 1 to 10 percent by weight, preferred 20 anchored connection layer on the workpiece, wise 5 percent by weight, based on the boronizing with solid borating agents is included. the so-called paste borating is first applied to »e- 5. Borating agent according to claim 1 to 4, applies, in which on the workpiece a paste characterized in that this is applied from 75 to from boron carbide, cryolite (Na ₃ AlF ₆ ) as a flux 85 percent by weight, preferably 79 percent by weight 25 and a binder will. The paste carried on percent boron carbide, 10 to 20 percent by weight, is first dried and then preferably 16 percent by weight borax and 1 heated in the high-frequency inductor, for example about 10 percent by weight, preferably 5 percent by weight at 1200 ° C. The advantages of this percent decay Fluoroborate exists as an activator. rens consist in shorter treatment times and the 30 possibility of partially borating; the main disadvantage of this method is to be seen in the fact that Powder particles from the boronating agent on aie Surface are welded, which leads to a very poor surface texture.
35 Because all of the procedures outlined above are in Boriding is a surface treatment process that has not been fully satisfactory in practice Treatment of metals, especially steel, by more recently boriding with powdery materials Metals with tough, wear-resistant tops- facing boronizing agents, though earlier surface layers are provided. Attempts in this area had shown that on Boriding has been encountered in practice for a long time 40 this way only thin porous layers are formed, of greater interest and hence several attempts using amorphous boron Boriding process has become known, all on the alone or in a mixture with aluminum oxide as Brsis of chemical or electromechanical reactive extenders only resulted in the use of protection between a boron-releasing medium and or activation gases, e.g. B. hydrogen, or im a metal, for example iron, at temperature and vacuum to form layers of sufficient thickness, but which ren based above about 600 ° C. The boron donating were still faulty. Besides, you had to In the various processes, the medium can have very high boronization temperatures and for a very long time be shaped, liquid or solid. Apply borrowing times. Because of the low ap- Boriding in the gaseous phase, i.e. H. with relative effort, the process appeared to be more gaseous in spite of that. Boronizing agents have become interesting from the economic point of view. For economic and technical reasons only in It is for the improvement of the boronization process Can enforce individual cases. Boron halides, diborane have also been proposed as gaseous boron and powdered borating agents, to compounds the powdered boron and certain inorganic and organic boron agents in conjunction with an activator such as BCI ₃ , BBr ₃ , (CH ₃ ) ₃ B and ( Use C ₂ H ₅ ) _S B 55. It is known, for example, that amorphous boron activated by ammonium chloride in pure form as well as in strong dilution with hydrogen are used. Can be ab-. But even after the activation, seen from the fact that all gaseous boronization goods are still very long treatment times at high medium extremely expensive, their temperatures are required to ensure sufficient layer handling in individual cases, e.g. B. to achieve diborane, 60 thick. It can also be made more difficult with regard to its high toxicity. The hard surface layers firmly produced by boronizing with powdered boronizing agents are often found that these processes are economically holey and contain considerable amounts of corrosion and technical aspects because of the high annealing products. Quite generally, it can be said that the temperatures and the long annealing times have not yet proven themselves and are satisfactory in the boronizing processes with gaseous boronizing agents aimed at usable layer thicknesses.
As a result, practice does not apply. The invention is based on the object of active Boim working with liquid boronizing agents has to find vators which, when boronizing in powder