**The New Generation of Diamond Wheels with Vitrified (Ceramic) Bonds**

Barbara Staniewicz-Brudnik, Elżbieta Bączek and Grzegorz Skrabalak

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59503

### **1. Introduction**

Modern, composite materials: non-ferrous metal alloys reinforced with hard particles, wood composites, plastic composites reinforced with glass fibers, nickel super-alloys (Hastalloy, Waspalloy, Inconel 718, Udimet720) and titanium Ti6Al4V, TiAl) [1-5] requires the develop‐ ment of technology taking into account abrasive tools with new binders [6-9].It is emphasized that provided affective work tools in the optimal adjustment of the characteristics of grinding machines, machining parameters, the characteristic of tools and a method of cooling and dressing. Typical bonded abrasive tool includes: super hard grains (diamond cubic boron nitride, mono-or microcrystalline microstructure), filler(corundum, silicon carbide, boron nitride etc.), binder (sintered metal, electroplated, resin, ceramic, hybrid), modifiers (homog‐ enizers, greases), body (metal, ceramic, polymer). Currently as bonded abrasive products are mainly used synthetic diamond or cubic boron nitride grains. Significant diamond grains producers were shown in table 1 [10]


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#### **Table 1.** Significant producers of diamond grains

**Producer**

54 Sintering Techniques of Materials

Element Six, USA

Gems Superabrasives,

Kingray New Materials & Science Technology

Changha 3 better ultra HARD MATERIALS,

China

Lands, USA

Co., China

China

**Trade name of diamond**

RBI -

SPR

PDA 657

PDA 321 PDA 311 PDA 211

GRD 10 GRD 20

JRI – typ A

MBD 6

**Grains morphology Application**

uncoated Irregular shape, medium friable crystals grinding of tungsten carbides and

microchipping structure, friable Grinding of cermets and elements of

LS 070 Ultra friable, irregular shape Specialized grinding benefiting from

JRI – typ B irregular shape Grinding of nonferrous hard alloys

Precision grinding and finishing of tungsten carbide and carbide,

PCD inserts

It is suited for used in less applications where sharp cutting characteristic are important

Grinding of soft Stones cutting,, sharpening, grinding ceramics and

Grinding lapping, polishing of cemented carbide, special steels,

Grinding stones ,ceramics, polishing of hard materials optical glass

Grinding of hard alloy, non-ferrous metal, polishing of natural diamond

Fine processing ceramics, optical glasses, grinding, polishing of

glass, natural stone

grinding

technical ceramic

rubber

RVG Irregular shapes, medium friable crystals

of crystals

LS 600F Uniform, blocky friable

MBD 4 Sharp crystal shape

sharpness

SMD 690 Premium grade grain with high strength and great thermal stability

RVD Irregular crystal shape preferably self-

policrystallic shape, low hardness

RVE Friable and strong self-sharpness,

grinding of RVG 800 Irregular shape, superior free capabilities due to controlled micro fracturing mode

> Uncoated economic grade grain, the friability of SPR enables controlled diamond fracturing, wheel selfsharpening and free cutting action

Multi crystal shape, consisting of many micro crystals with slight friability enable excellent self- sharpness

LS 100 Friable, irregular shape free cutting crystals

**Figure 1.** Synthetic industrial diamonds production [1]

In general, monocrystalline grains, used for tools with vitrified bond are assigned for grinding of flat and shaped surfaces, for example grinding of internal surfaces of Titan alloys and sharpening (fig. 2). Microcrystalline grains are complexes consisting of collection of small microcrystals with sizes ranging from one to a few microns, characterized by a higher mechanical strength, and higher ductility of monocrystalline grains (fig. 3)

**Figure 2.** Microcrystalline diamond grains magn.: a) 400x, b) 2000x

**Figure 3.** Monocrystalline diamond grains magn.: a) 200x, b) 2000

The microcrystalline grains are recommended for grinding operations, where surface quality is the main processing criterion. The fillers can be alumina, silicon carbide, tungsten, zirconium silicate etc. It is assumed that the filler, introduced into the binder, protects the seed prior to the dynamic action of chips (typically having a higher temperature) and that increases the strength properties of the sinter, the thermal resistance and wear resistance, also taking part in the grinding process. The binder is a factor connecting the embankment of grain in the wheel causes the maintenance work until the grains have sharp edges, thereby induced on the selfsharpening effect of the grain. The efficiency of binders application provide features such as adequate strength of fixing force of particles in the binder, wear resistance, the possibility of sintering of the tools below temperature of graphitization (diamond) or active oxidation (CBN), having long thermal conductivity allowing for intense heat removing from the grinding zone without accumulation, the coefficient of thermal expansion close or identical with the coefficient of thermal expansion of the abrasive grain, proper hardness and strength, no reaction with work-piece material [6-8, 11-13]. Vitrified binders are primarily glass or devitri‐ ficate from the multicomponent system, received from synthetic chemicals with very high purity [6, 9].

They are divided into a low-melting binder (sintering temperature up to 730o C), medium (sintering temperature up to 880o C) and a high-melting (sintering temperature above 900o C). The most characteristic systems are borosilicate glasses modified with various oxides (Na20, Li20), calcium-silicate glasses, modified by V205, Fe203 or P205, lead-borosilicate devitrificates, barium-borosilicate with the addition of bismuth oxide. The most famous research centers dealing with binders for super hard tools including vitrified bond are located in Worceaster (GE company-USA), Aachen(RWTH-Germany), Sankt Petersburg (Ilyich company –Russia), Kiev (Institute of Super hard Materials –Ukraine), Zhengzhou (Zhengzhou Concern Hongtuo Superabrasive Products Co.-China). The Institute of Advanced Manufacturing Technology is conducting researches aiming at obtaining ceramic binders for super abrasives tools with controlled physical and mechanical properties and testing tools containing these binders. This publication shows the results of research of new vitrified (ceramic) binders and testing of grinding tools with these binders for the latest generation of composite BNDCC (boron nitride dispersive in cemented carbide) of various grit size of cubic boron nitride grains.
