DE1796215A1 - Process for boronizing metals, in particular steel - Google Patents

Description

Institute for hardening technology

Bremen-Lesum

lesumer Heerstraße 32

Process for boronizing metals, in particular steel

Boriding is a surface treatment process of metals, in particular steel, by means of which metals are provided with hard, wear-resistant surface layers will·

Boriding, for example, has met with greater interest in practice for a long time and several boriding processes have been known to date, all of which are based on chemical or electrochemical reactions between a boron-releasing medium and a metal, for example iron, at temperatures above about 60O ⁰ C. The boron-releasing medium can be gaseous * liquid or solid in the various processes.

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ORIGINAL INSPECTED

Boriding in the gaseous phase, that is to say with gaseous boronizing agents, has so far only been able to establish itself in individual cases for economic and technical reasons. Boron halides, diborane and certain inorganic and organic boron compounds such as BCl ,, BBr ,, (CH ₅ J ₅ B and (02Hc) ₅ B, both in pure form and in strong dilution with hydrogen »can be used as gaseous boron-releasing agents. Apart from the fact that all gaseous boron agents are extremely expensive, their handling is made even more difficult in individual cases, e.g. in the case of diborane, due to their high toxicity. The hard surface layers produced are often pitted and contain considerable amounts of corrosion products. In general, it can be said that the boronizing processes with gaseous boronizing agents have not proven themselves and are consequently not used in practice

When working with liquid boronizing agents, there are three options, namely boronizing in molten salts and without electrolysis and in aqueous solutions with high-frequency heating first two procedures are sswar

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selir v / economically, but their applicability becomes through Creation of a difficult to wash off Schraelzschieh

on the workpiece, impaired by the unsatisfactory temperature retention, by corrosion of the crucible materials and by the effect of senate (when the electrolysis is used). The third method, namely boriding ii: aqueous. Solutions turn het no practical significance is because due to the neaktivität many Borvex'biiidungen lüit V.asser for this work, only borax and Borsäureanhyarid inira ^ e come, however noble these connects no Sorpotential achieved v / was grounded, the sum of a diffusion sufficient amount of boron in the surface is sufficient; as a result, a firmly anchored connection layer does not form on the workpiece.

Boriding with solid boron agents is the first one the so-called paste boring applied, with v / elchem on the workpiece a pc-ste made of loric carbide, Cryolite (Ea-zAlJ! ^) As a flux and a binder applied v / ird. The paste applied is first dried and then heated in the high frequency inductor,

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BATH ORIGINAL

for example, about 3 minutes to 12UO ⁰ C. The advantages of this process are shorter exposure times and the possibility of partial boriding; The main disadvantage of the process is that powder particles from the boronizing agent are welded onto the surface, which leads to a very poor surface quality.

\ veil all methods described above have not fully satisfied in practice, it has turned ^ smitteln iaehr boriding with powdered Borierun recently, although previous experiments had found in the art, αε, β on this We _t e only thin porous Layers arise. Attempts using amorphous boron alone or in a mixture with aluminum oxide as an extender only led to layers of sufficient thickness when using protective or activating gases, eg hydrogen, or in a vacuum, but these were still defective. In addition, very high boronization temperatures and very long boronization times had to be used. Because of the low outlay on equipment, the process still appeared interesting.

BATH ORIGINAL

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It has also already been proposed to improve the boriding process with powdered borating agents v / Orden to use the powdered boronating agents in connection with an activator. This is how it is, for example known that amorphous boron can be activated by ammonium chloride. But even after activation were still very long treatment times at high temperatures required to achieve sufficient layer thicknesses. So it can also with regard to the boronization Powdered boriding agents are found that this process in economic and technical terms because of the high annealing temperatures and the long annealing times to achieve usable layer thicknesses not fully satisfy.

The invention is based on the object of activators 2iU find that when boronizing in powdered agents the achievement of technically usable layer thicknesses with shorter annealing times and / or low annealing temperatures make possible.

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The object is achieved according to the invention by using a Group of compounds dissolved as activators, by the the disadvantages outlined above can be eliminated. In the proposed according to the invention Group of compounds, the powdery borating agents should be added as activators, they are fluoroborates or boron fluorides · »

The use of fluoroborates is $ var from boronation in the liquid phase, e.g. in salt baths, known, but the behavior and the mode of action of the Pluoroborate completely different in this process · In the Boronization in salt baths consist of salts or salt mixtures, the latter at the proposed treatment temperature are liquid and in which elemental boron can be dissolved or dispersed. By the salt »which serves as a solvent for elemental boron in the molten state, it can also be, for example Act fluoroborates. Apart from the basic ones Difference between the two processes, i.e. boronization with molten salts, in which boron is dissolved, and boronization with powdery boronizing agents, which now

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ü Fluorotorate added as activators \. earth, is also the Viirkun ^ sv / eise of the Fluoro-Loratü in the two cases completely different. For example, when using aer Pluoroborate e.1s solvents, their high effects Zeri'c.llgeschv / indiLkeit very disturbing. With the boriding with powdered boronating agents, however, much It has now been found, ger & de the rapid decay of the fluoroborates, or they act as activators for this process; laren v; ert full spawns. At dieecr Arceitev / eise comes et; At the moment it is crucial to keep the heat as possible ßclüiell is checked in gear. Using the Fluoroborates as activators for powdery boriding agents is to be viewed as completely new and leads, as will become clear from the following, to considerable, unforeseeable advantages.

The invention relates to the use of fluoroborates as activators for powdery borating agents or mixtures when boronizing metals, especially steel. The powdery boronizing agent can be ferroboron, amphesian boron, boron carbide or borax or a mixture act of these substances

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BATH ORIGINAL

The invention also relates to pulverulent boronizing agents containing activators, in particular for boronizing of steel, but also other metals, which consist of boron carbide and a fluoroborate as an activator of boron carbide, mixtures of boron carbide and borax, ferroboron or amorphous boron can also be used according to the invention will.

The ones used as boronating agents with fluoroborates activated substances or substance mixtures can optionally be added as an extender, which to prevent the powder from caking.

The fluoroborates added as activators can preferably be sodium, potassium or ammonium fluoroborates Act.

According to the invention, the activator is used in the boring agents in amounts of 1 to 10 percent by weight, preferably about 5io, based on the boring agent.

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According to a preferred embodiment of the invention c is the boronizing agent which is used to boronate Metals, especially steel, is extremely suitable, from 7 ^ -85 percent by weight, preferably 79 percent by weight Boron carbide, 10-20 weight percent, preferably 16 φ

Percent by weight of borax and 1 to 10 weight percent, preferably 'ö weight percent, fluoroborate as an activator.

By using the fluoroborates according to the invention as activators in powdered boriding agents can ■ in all previously known methods (which work with powdered boriding agents) the layer thickness in comparison to increase the layer thickness that can be achieved with non-activated boriding agents; on the other hand ^ is it possible to use a boride layer of the same thickness in considerable

lent a shorter time or at a lower boriding temperature to create. The activators according to the invention, i.e. the fluoroborates, also result in powdery boriding agents a stronger activation than previously known activators, e.g. ammonium chloride.

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- ίο -

The effect of the activator is due to the used boriding agent addicted. As could now be determined, the effect is strongest in ferroboron and boron carbide-borax-Geraischen, while amorphous boron and mixtures containing amorphous boron are less strong is still better than the known activators.

In principle, a wide variety of fluoroborates can be used. However, it has been shown that alkali fluoroborates. such as sodium fluorate, HaEP, or potassium fluoroborate, KBP., and ammonium fluorotorate, (IIH ^) BIP, are more suitable than alkaline earth and heavy metal fluoroborates.

The following exemplary embodiment serves to further explain the invention.

example

^ Facilitated purposes to Ver was first boration of a steel with low carbon content in a mixture of 84 weight percent boron carbide, B * east and 16 percent by weight of borax, Na ₂ B-CU performed · If a workpiece,

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for example made of steel, in this r-ioi.ti. ^ tiviertwii mixture 6 hours Lsi 1wcv ° C "ceh- ~ .n; ielt, a very unreal :."^?; ii ^ .e layer, csron Sxtlive sv / i see 0, ObO and 0,1c.-j λκ :: ε a ^r an ^ t.

iii .-- echliaiend vurae a v / eit ^ re Borierun _t v.obei uasselce '. ■■'ir-'stüc -us Stahl ecenialis in an o-euiiach from 5υi \ ^ r "bid unu Jora; - :, v / elches jeaoch with L: liuiüfluorotort: .t activated usr, terielten v.urae.

Ll "-i activicrtt Lorier ^ ittal vies a Zuc Einmensetzurn-. Of 79 G-ev / ichtcv-roz & nt S_C, 16 weight. ^:. · Ο_; sr.t l ^ cS.O ^ and ^

In view of the rociiit i ^ öi ¹ on. Under de.,.! Eichen 2eh. £ .r.ülun "x-

^ en v / ie above-berthing th, a äßige, O ₁₂₄₀ bilaete on thick layer.

Hit help of the ür-Liiiäun, =: can thus be divided nit powder boronizing agents a considerable and achieve unpredictable improvement.

209813/0547 bad OR.G.NAL

Claims (1)

tent claims (1.)) The use of fluoroborates as activators for powdery boronizing agents or mixtures when boronizing metals, especially steel. 2.) The use of fluorocorates according to claim 1, characterized in that the powdery boronizing agent made of ferroboron, amorphous boron, Bork & .rbiü or borax or a mixture of these substances. 3.) Activator-containing powdery boronating agent, In particular for boronizing steel, consisting of boricartide and a fluorotorate activator. 4.) Boriding agent according to claim 3, characterized in that that it consists of a mixture of boron carbide and borax as well as fluoroborate as an activator « 209813/0547 & ® ORIGINAL / a $ o) Boronizing agent in powder form, in particular for Boronization of steel, consisting of a mixture of Perroboron and 3? Luoroborate as an activator, to which aluminum oxide may also be added as a streel agent. 6.) Powdered boronizing agent, especially for boronizing steel, consisting of a mixture of amorphous boron and fluoroborate as an activator, to which aluminum oxide may be added as an extender. 7 «) borating agent for use according to claim 1, characterized in that the activator consists of sodium, potassium or ammonium fluoroborate. 8.) Borating agent for use according to claim 1, characterized in that the activator in amounts of 1 to 10 percent by weight, preferably about 5 $, based on the boronating agent. 9.) boronizing agent according to claim 4, characterized in that 75-85 percent by weight, preferably 19 % of the same made of boron carbide, 10-20 percent by weight, 209813/0547 preferably 16 ^ ύ, made of borax and 1 to 10 percent by weight, preferably 5 $ j from Fluorofcorat as activator exist. Bremen, September 12th * 1968 For the applicant: Di; ^; η '*, ί;:; ^{; w} Meissner ;),.) [. inf., h i '^ i Bu.ie 2 8 Bremen 3liiv-, yKtroöe2l, · Jteton 34 2Ö10 Applicant:
ι Institute for hardening technology Bremen ^ Leeum
j iesumer Heerstraße 32 209813/0547