Lateral Cracks Research Articles

Determination of stress waves and their effect on the damage extension induced by surface defects of KDP crystals under intense laser irradiation

The residual crack defects on the surface of potassium dihydrogen phosphate (KDP) crystals are the bottleneck that limits the improvement of laser damage resistance in the application of high-power laser devices. The multiple stress waves introduced by these residual surface lateral cracks on crystals under laser irradiation are the main inducement for damage extension and reduction of laser damage resistance. However, the coupling of these stress waves complicates their propagation in the crystal, and the interaction mechanism between each stress wave and laser damage has not been quantitatively characterized. Herein, a laser damage dynamic model for surface lateral cracks is constructed to reproduce the dynamic behaviors of the evolution of micro-defects to sub-millimeter damage pits under laser irradiation. Combined with the time-resolved pump and probe technique, the distribution of stress waves induced by lateral cracks was detected in situ to determine the type of stress waves. Then, the initiation and extension of laser damage were analyzed quantitatively to establish the correlations between different stress waves and damage extension. It is found that the longitudinal, shear, and Rayleigh waves induced by lateral cracks lead to large crush zones on the surface of KDP crystals, as well as butterfly-like damage sites accompanied by a large number of cracks at the bottom in the longitudinal section. The scale of the damage site can reach up to approximately 150 µm for lateral crack defects with large surface widths. This study ultimately reveals the physical mechanism of damage evolution induced by lateral cracks, providing effective guidance for developing control standards of surface crack defects during optical ultra-precision machining processes. This is of great significance for the improvement of laser damage resistance of KDP crystals in high-power laser systems.

Damage evolution of the coating/substrate system TiN/X2CrNi18-9 under high indentation loads: experimental and numerical study

Hard coatings, in particular TiN, are widely used as coatings for cutting tools and in the agri-food industry. In the literature, however, few characterizations of hard coatings can be found which define the minimum applied load when the coating starts to fail. In the present study TiN coating was deposited on stainless steel X2CrNi18-9. Vickers and Brinell indentation tests with a wide load range were performed. The main results revealed that the increase of the applied load in Vickers and Brinell indentation influenced the coating and coating/substrate damage evolution. SEM investigation of the Vickers indentation area shows five modes of damage: inclined cracks, radial cracks, lateral cracks, edge cracks, and shear steps. Each damage mode occurs at a specific load range. Parallel cracks already appeared at the edges of the indents at the lowest load of 2 N. For Brinell indentation, cracks start in the coating only at loads higher than F = 307 N. The SEM examinations present damage modes such as circumferential cracks in the border and additional circular cracks in the center of the indent, creating a crack network. Numerical simulations of Brinell indentation were carried out in order to determine the stress distribution in the indent. The comparison of the numerical simulation results with the experimental findings revealed that the coating started to fail at a stress range above 5735 MPa which corresponds to a normal load range of higher than 307 N in Brinell indentation tests. At a load of 613 N cracks were observed.

INDENTATION OF ELECTRON-IRRAUDED FILMS OF DIAZOQUINONE NOVOLAC
 PHOTORESISTS ON SILICONE

The strength properties of FP9120, SPR 700 and S1813 G2 SP15 diazoquinone novolac photoresist films
 on silicon irradiated by 5 MeV electrons with a fluence of 3 1016 cm-2 were studied by indentation. Misprints of
 the microindenter in films of diazaquinone novolac photoresist are barrel-shaped, which indicates the presence
 of tensile stresses that form during film drying. A destruction zone with radial and lateral cracks was observed
 around the indenter prints, forming a pattern in the form of "butterflies". It has been established that during longterm
 storage and irradiation of films of diazoquinone novolac photoresists, an increase in the values of the true
 microhardness of the films takes place, which is due to the cross-linking of novolac macromolecules in the bulk
 of the polymer.

Ballistic response of skin simulant against fragment simulating projectiles

The response of biological phantoms against high velocity impact is actively sought for applications in defense, space, soft robotics and sensing. Towards this end, we study the ballistic response of silicone based skin simulant against fragment impact. Using a pneumatic gas gun setup, six chisel-nosed and three regular shaped (sphere, cylinder, and cube) fragments were impacted on the skin simulant. The resulting skin simulant response was studied in terms of ballistic limit velocities, energy densities, failure pattern, and the mechanics of interaction. The results indicate that the shape of the fragment affects the ballistic limit velocities. The ballistic limit velocities, energy densities of the chisel-nosed fragment simulating projectiles were relatively insensitive to the size (mass), except for the smallest (0.16 g) and largest (2.79 g) chisel-nosed fragment. For the same size (1 g), ballistic limit velocities and failure are dependent on the shape of the fragment. The skin simulant failed by combined plugging and elastic hole enlargement. Failure in the spherical fragment was dominated by the elastic hole enlargement, whereas plugging failure was dominant in all other fragments. The spherical, cylindrical, and chisel-nosed fragments created circular cavities, and the cubical fragment created a square cavity. In the case of the spherical fragment, slipping of the fragment within the skin simulant was seen. Cubical fragments created lateral cracks emanating from the corners of the square cavity. Interestingly, for all the fragments, the maximum deformation corresponding to the perforation was lower than the non-perforation indicating rate dependent, stress driven failure. The maximum deformation was also dependent on the shape of the fragment. Overall, these results provide unique insights into the mechanical response of a soft simulant against ballistic impact. Results have utility in the calibration and validation of computational models, design of personal protective equipment, and antipersonnel systems.

Experimental and Simulation Study on the Hard Rock–Breaking Characteristics of Disk Cutter under the Water Jet Precutting Kerf

The effect of water jet kerf depth (H) and cut spacing (S) on the rock-breaking performance of a disc cutter under water jet precutting kerf was investigated through a full-scale linear cutting test and numerical analysis with a discrete element method (DEM). Rock-breaking force, rock chip, and rock-breaking efficiency are used to evaluate the rock-breaking performance. The rock-breaking experimental results show that the rock failure patterns are closely related to H and S, and distinct rock failure patterns are shown for the different rock-breaking parameters. In addition, this study reveals the variation law of rock-breaking force and specific energy (SE) consumption with H and S. The difference in crack expansion between rock-breaking under conventional and precutting kerf conditions was compared with numerical simulations. The lateral cracks tend to expand toward the bottom of the precutting kerf and are more prone to produce large-sized rock chips in the precutting kerf condition. In addition, the increased H promotes the expansion of the vertical and lateral cracks, which resulted in different rock failure patterns. Therefore, the numerical, and experimental results show that the rock-breaking of the disc cutter under the precutting kerf conditions is promising, which significantly improves the rock-breaking performance of the disc cutter in hard rock conditions.

Subsurface damage model in single and double scratching of fused silica with a blunt indenter

The subsurface damages (SSDs) generated during abrasive processes greatly impact the service performance and life of the devices or components made from brittle materials. The abrasive processes can be simplified as multi-scratching where the abrasive grits tend to be blunt. Consequently, the evaluation of SSDs in the scratching with a blunt indenter is worth of study. In this paper, by extending the blunt indenter-related indentation fracture mechanics and deriving the analytic equations for the contact areas between the indenter and the workpiece, a theoretical SSD depth model is first developed for the single and double scratching of brittle materials. The model correlates the depth of subsurface cone, median, and lateral cracks with the indenter nose radius, scratching depth, residual depth, normal load, tangential load, scratch spacing, and workpiece material properties. To validate the model, scratching experiments are carried out on polished fused silica under different scratch spacing, and the effects of scratch spacing on the surface/subsurface morphologies of scratch grooves, scratching load, and friction coefficient are investigated experimentally. The results show that the radial, cone, median, and lateral cracks are coexistent in fused silica. The second scratching leads to an increase in the fracture degree of the first one, while the SSD depth in double scratching approximates that in single scratching. A small scratch spacing leads to an increase in tangential load or friction coefficient while a decrease in normal load. It is proven that the theoretical model can accurately determine the upper/lower bounds of scratching normal load and subsurface crack depth considering the workpiece fracture degree. Moreover, it is revealed that the SSD depth increases slightly with an increased friction coefficient. This research contributes to the evaluation of SSDs in the abrasive-processed fused silica or similar brittle materials.

Nanoscratch Testing of 3Al2O3·2SiO2 EBCs: Assessment of Induced Damage and Estimation of Adhesion Strength

In this study, the structural integrity of mullite (3Al2O3·2SiO2) films, deposited on silicon carbide (SiC) substrates using chemical vapor deposition (CVD), was investigated via increasing load nanoscratch tests. The films were configured by mullite columns of stoichiometric composition growing from a silica-rich layer in contact with the SiC substrate. Controlled damage was induced in the 3Al2O3·2SiO2 films at relatively low scratch loads. Radial and lateral cracking were applied until final delamination and repeated chipping were achieved as the load increased. The intrinsic integrity of the 3Al2O3∙2SiO2 film and the performance of the coated 3Al2O3·2SiO2/SiC system, regarded as a structural unit, were analyzed. With the aid of advanced characterization techniques at the surface and subsurface levels, the configuration and morphology of the damage induced in the coated system by the nanoscratch tests were characterized, and the scratch damage micromechanisms were identified. Finally, the adhesion of the film, in terms of energy of adhesion and interfacial fracture toughness, was determined using different models proposed in the literature. The results from this investigation contribute to the understanding of the mechanical performance and structural integrity of EBC/SiC-based systems, which over the past few years have increasingly been implemented in novel applications for gas turbines and aircraft engines.

Crystallization in a soda–lime‐silicate glass after high pressure

AbstractThis work explored the permanent changes a high pressure (HP) processing could cause on nucleation, Raman vibrational modes, thermal, and mechanical properties of the Na2O • 2CaO • 3SiO2(N1C2S3) glass. It was shown that, with higher pressure values, the number of nuclei per unit of volume,NV, has decreased. Raman spectra showed no significant changes in the vibrational modes; however, the differential thermal analysis performed indicated that the glass transition temperatures,Tg, were higher than the pristine glass sample and that HP caused the glass to be less stable. The Vickers indentation radial cracks remained constant; however, the lateral cracks increased in size, indicating that the glass is more stressed after HP, and therefore, the relaxation time for nucleation will be higher, loweringNVfurther, as observed.

Comment on “Lubauer J, Lohbauer U, Henrich M, Munz M, Lube T, Belli R. Intricacies involving the evaluation of fracture toughness obtained by the surface‐crack‐in‐flexure method. J. Am. Ceram. Soc., 2022;105(12) 7582–7599”

AbstractWe have evaluated over fifty materials using small semi–elliptical controlled surface flaws with the Newman–Raju factors. Although occasionally there were nuances and peculiarities, the results were sound and comparable to other methods. So, despite the lengthy discussions and numerous plots in Lubauer et al.’s paper, what is evident is that if one simply follows the guidelines in ASTM C 1421 and the other standards for most ceramics including the SL200B sintered silicon nitride, and polish off the recommended 4.5 to 5 h material, one will obtain the correct results. Excessive indentation forces and excessive material removal to obtain sharp corner, shallow surface cracks are unwise. Removing more than 5 h should only be done to remove lateral cracks. In such cases the Strobl et al. solutions may be useful. These solutions are an interesting alternative to the reputable Newman–Raju factors, but much more experience and verification is needed before they can be accepted. They and the extension of their analysis for precrack angles χ < 70° need to be vetted in a major engineering journal.

Subsurface deformation and crack propagation between 3C-SiC/6H-SiC interface by applying in-situ laser-assisted diamond cutting RB-SiC

Reaction-bonded silicon carbide (RB-SiC) is considered as an excellent optical material in aerospace engineering. However, the multiple complex interfaces and high hardness make it difficult to be precisely machined. In this research, the in-situ laser-assisted diamond cutting was applied to precisely machining RB-SiC. Firstly, Raman spectroscopy was adopted to identify 3C-SiC and 6H-SiC components in RB-SiC. As following, the in-situ laser-assisted diamond cutting was experimentally carried out to analyze the subsurface deformation and fracture in detail. It was clarified that the cross slips and high-density stacking faults significantly enhance the plastic deformation of RB-SiC. Moreover, the dislocations rapidly plugged at the intersection of 3C-SiC/6H-SiC interfaces resulting in the lateral crack which propagates along the [111]//[0001] direction.

Microstructure and mechanical analyses of Ti6Al4V/B4C composites on Ti6Al4V substrate: Effect of laser power on multiple track laser metal deposition

Components used in many manufacturing applications especially in the defence, automotive and aerospace are required to meet certain properties, such as elastic modulus, toughness, resistance to wear and corrosion. Additive manufacturing (AM) is a technique used for the fabrication of layer-by-layer geometries via three dimensional (3D) mechanisms at a certain process parameter. Titanium alloy and boron carbide (Ti6Al4V/B4C) composites coatings have been successfully fabricated on titanium alloy (Ti6Al4V, grade 5) by laser metal deposition (LMD) of additive manufacturing (AM) process. Microstructure analysis of the fabricated multiple clad is characterized by optical and scanning electron microscopy. The obtained multiple tracks show that the coatings are profound with TiC and TiB phases with dendrites of TiC particles in the coatings. The evolving microstructures of the deposited coatings at a laser power of 1000 W and 1200 W with a scanning speed of 1 m/min exhibit some lateral cracks which is associated to the brittle nature of ceramic boron carbide in the clad zone. The atomic level characterization of the coatings is determined through the surface roughness obtained by atomic force microscope (AFM). Microhardness analysis is performed at the cross-section surface of the coatings by Vickers pyramid indentation at 300 gf load with dwell time of 10 s on Zwick Roell microhardness tester. From the samples investigated, sample at a laser power of 1200 W has the highest hardness value of 548 HV0.3/10s.

Oxide formation mechanism of a corrosion-resistant CZ1 zirconium alloy

Tailoring microstructure and microchemistry by altering elemental compositions and thermomechanical treatment parameters enables superior corrosion performance in zirconium alloys for nuclear applications. However, our understanding of the relationship between various defects and the corrosion process remains limited in the newly developed zirconium alloys. Here we report the oxide formation mechanism of a CZ1 zirconium alloy with corrosion resistance surpassing many other zirconium alloy systems, such as Zircaloy-4 and Zr-1Nb-1Sn alloys. Autoclave experiments of CZ1 alloy and Zr-1Nb-1Sn model alloy were performed in 360 °C water for up to 820 d. We quantitively determined oxide phases by transmission Kikuchi diffraction (TKD) and examined lateral cracks, nano-porosity, and second-phase particles in oxide scales by transmission electron microscopy (TEM). Compared to the Zr-1Nb-1Sn model alloy, CZ1 alloy with lower Nb and Sn concentrations has shown smaller and lower-density lateral cracks but slightly larger oxide grains, reducing the diffusion route for oxidating species. Using analytical scanning and transmission electron microscopy, we demonstrate that due to the lower content of Sn (∼0.9 wt.%), there is less tetragonal ZrO2 phase formed in the oxide, and the level of tetragonal to the monoclinic phase transition is reduced. Although the Nb content (0.1 wt.%–0.3 wt.%) is lower than the solid solution limit of Nb in Zr, by introducing minor elements such as Fe, Cr, and Cu, there are still a reasonable number of second-phase particles to relieve the high stress associated with the metal-to-oxide transformation. These mechanisms have substantially changed the density and distribution of lateral cracks in the oxide, thus reducing the corrosion rate of zirconium alloys.

The rock fragmentation and crack propagation under TBM tunneling based on particle flow code

Abstract The rock fragmentation and crack propagation of anisotropic rock induced by tunnel boring machine (TBM) tunneling is studied in this paper. First, a numerical model based on the 2D particle flow code (PFC2D) is established and calibrated to reveal the four stages of rock fragmentation. In Stage I (indentation depth 0–0.4 mm), the indentation force beneath the cutterhead increases and decreases dramatically with the accumulation and release of mechanical energy. Such a phenomenon indicates that a hydrostatic core (crushed zone) can be observed. In Stage II (indentation depth 0.4–1.1 mm), many median cracks propagate dramatically with the indentation force. Meanwhile, the hydrostatic core is pushed because the mechanical energy of the cutterhead is reaccumulated in the specimen. In Stage III (indentation depth 1.1–2.6 mm), lateral cracks begin to develop due to the further increase in indentation depth. In Stage IV (indentation depth 2.6–5 mm), the lateral cracks and median cracks continue to propagate, and rock chips can be found on the sides of the cutterhead. Then, with increasing confining pressure, lateral cracks begin to gradually develop and the maximum angle of lateral cracks is 70.5°. Furthermore, the magnitude of the intrusion velocity can seriously influence the evolution of the indentation force during Stages III and IV because of the accumulation and release of mechanical energy. The accumulation and release of mechanical energy are more obvious with a higher intrusion velocity of the cutterhead.

Cracking behavior of sisal fiber-reinforced clayey soil under wetting-drying cycles

Climate variables such as rainfall and high temperature can influence clayey soil moisture and the development of cracks, which can further give rise to environmental and geological disasters. This study investigates the influence of different soil thicknesses, fiber content, and three wetting-drying cycles on soil moisture evaporation and the formation and development of cracks. A photographing system and weighing equipment are used to track the changes in soil mass and cracks during three wetting-drying cycles. Resulting photos of the cracks are quantified and analyzed by image processing technology. Results show that the thicker soil layer can prolong the normal evaporation phase and reduce the stress concentration on the surface, resulting in a delay in cracking. However, this could lead to the development of wide cracks and the formation of shallow ditches, which is an irreversible process with multiple wetting-drying cycles. Sisal fibers are able to effectively solve the aforementioned problems in terms of, reducing the development of longitudinal and lateral cracks and shallow ditches. This further reduces the rate of sudden cracking and helps to maintain the soil’s structural integrity. The healing ability of wetting-drying cycles for cracks increases with the sisal fiber content. These findings indicate that soil cracking is influenced by many factors, though there are no absolute factors that promote or hinder the development of cracks. Therefore, methods that can amplify the positive effects while weakening the negative effects should be explored.

Understand anisotropy dependence of damage evolution and material removal during nanoscratch of MgF2 single crystals

To understand the anisotropy dependence of the damage evolution and material removal during the machining process of MgF2 single crystals, nanoscratch tests of MgF2 single crystals with different crystal planes and directions were systematically performed, and surface morphologies of the scratched grooves under different conditions were analyzed. The experimental results indicated that anisotropy considerably affected the damage evolution in the machining process of MgF2 single crystals. A stress field model induced by the scratch was developed by considering the anisotropy, which indicated that during the loading process, median cracks induced by the tensile stress initiated and propagated at the front of the indenter. Lateral cracks induced by tensile stress initiated and propagated on the subsurface during the unloading process. In addition, surface radial cracks induced by the tensile stress were easily generated during the unloading process. The stress change led to the deflection of the propagation direction of lateral cracks. Therefore, the lateral cracks propagated to the workpiece surface, resulting in brittle removal in the form of chunk chips. The plastic deformation parameter indicated that the more the slip systems were activated, the more easily the plastic deformation occurred. The cleavage fracture parameter indicated that the cracks propagated along the activated cleavage planes, and the brittle chunk removal was owing to the subsurface cleavage cracks propagating to the crystal surface. Under the same processing parameters, the scratch of the (001) crystal plane along the [100] crystal-orientation was found to be the most conducive to achieving plastic machining of MgF2 single crystals. The theoretical results agreed well with the experimental results, which will not only enhance the understanding of the anisotropy dependence of the damage evolution and removal process during the machining of MgF2 crystals, but also provide a theoretical foundation for achieving the high-efficiency and low-damage processing of anisotropic single crystals.

Landslides and sinkholes of the karst environment in the vicinity of the Ufa river

Introduction. As a result of the conducted route reconnaissance and geological engineering surveys, data about the development pattern of exogenous processes at a site adjoining the city of Ufa were obtained. This region is well studied due to the extensively developed karst. Although landslides are less prevalent here, their development is frequently connected with the karst intensification. Landslides, formed in sites of sinkholes and topographic lowering, are well represented in other regions of the Russian Federation. Aim. To study the characteristics of landslide formation. In addition, the mechanism of forming landslides, confined to rock massif decompaction zones, is analysed.Materials and methods. A mechanism of landslide formation in the sites of karst development is proposed. The work is based on the analysis of the results obtained in previous researchers of 1997, 2013 and 2017, interpretation of satellite images, digital terrain model and topographic, geomorphological and engineering-geological maps, as well as reconnaissance surveys. The peculiarity of engineering-geological conditions makes it possible to study the formation and development of two exogenous processes simultaneously (karst and landslides) in the selected area. The area under study included the exit section of Ufa city along the slopes of the Solotchi and Ufa rivers. According to the law established by Bondarik, Pendin and Yarg in 2007, “...some geological processes prepare others, which, in turn prepare the next ones, etc. and, as a result, so-called cascade processes develop...”. Exogenous geological processes of karst and landslides, developing in one section of the geological massif, are considered.Results. The formation of cavities is confined to the tectonic fracturing, along whose surface underground waters flow into the depths of the rock massif. The hydrodynamic zonation varies in time with the substraction of a filler and a release of previously formed cracks, cavities and voids. As long as the vertical pressure in soils and layer bearing capacity remain stable, no deformation of the massif above the cavity is observed. As a result of the study, the process sequence was presented for consideration, as well as the assumption was made about the lateral repulse crack deforming the slope surface after the formation of a block at the depth.Conclusion. The formation of karst sinkholes was demonstrated to intensify landslide processes on the slope surface.

Development of a method for the separate measurement of the growth of internal crack tips by means of the potential drop method

Under cyclic loading fatigue cracks can arise in the vicinity of the joints of clinched structures, which behave like internal cracks. In the simplest case, the two crack tips of an internal crack grow symmetrically to the joint and it is sufficient to measure the resulting crack length with the potential drop method. However, uneven growth of the two crack tips can also occur, so that the resulting crack is no longer arranged symmetrically to the joint. In order to be able to adequately monitor even an unsymmetrical propagation of internal cracks while the test is being carried out, a new general method has been developed with which the resulting crack length and the possible different propagation behavior of the two crack tips can be registered by simultaneously measuring two potential drops. The generality of the new method is verified by applying the method to two different specimen types. A specimen with a central hole and lateral cracks with different defined lengths is used to experimentally validate the method.

Analytical modeling of the stress field in scratching anisotropic single-crystal silicon

Single-crystal silicon is widely used in semiconductor and photovoltaic industries. However, the hard and brittle single-crystal silicon is highly susceptible to surface or sub-surface damage such as median cracks, radial cracks and lateral cracks during machining, which will affect the quality of the machined surface. This paper proposes an analytical model of the stress field in scratching single-crystal silicon to analyze the crack driving stress. An analysis of the anisotropic properties of single-crystal silicon and the factual location of the inelastic zone center is presented. In order to simplify the scratching process, the scratching-induced embedded center of dilatation (ECD) stress field is deducted based on the ECD stress field and the superposition principle. The stress field in the scratching single-crystal silicon (100) crystal surface was calculated to analyze the effect of the scratching stress field on crack nucleation. The normal load was found to be the main stress driving the nucleation and expansion of the median crack. The nucleation extension angle of the median crack decreases as the equivalent half-angle of the indenter increases. Scratching the single-crystal silicon (100) crystal surface in the [00–1] direction reduces subsurface median crack damage. Indenter depth increases residual stress, which can increase brittle removal of the material, resulting in the nucleation of the median crack. This study can provide a theoretical basis for refining the parameters of the scratching process and controlling the surface damage in scratching hard and brittle crystalline materials.

Analysis of crack initiation load and stress field in double scratching of single crystal gallium nitride

Precision processing such as grinding of single crystal gallium nitride is processed through complex interactions between many diamond particles. However, single-grain scratching can only study the basic performance of abrasive grain processing, and cannot study the mutual influence of multi-abrasive grain processing. Therefore, this paper studies the situation of double scratching. The influence of the distance between two scratches on the crack initial load has been studied by the analysis model during simultaneous double scratching and continuous double scratching. During continuous double scratching, when the separation distance L < 1.8b, lateral cracks on adjacent side of the second scratch nucleate and expand under a smaller initial load than single-indenter scratching, and the smaller the L is, the smaller the corresponding initial load of lateral cracks will be. When the separation distance is 0.4b and 0.8b, the median crack nucleates at the middle of two scratches. During continuous double scratching, the median cracks always nucleate and expand at the bottom of the second scratch.

Ductile-brittle transition mechanisms in micro-grinding of silicon nitride

Ductile grinding of brittle materials is essential for high precision applications and to maintain the strength and lifetime of the parts. The critical chip thickness of a brittle material defines a threshold for the lateral cracks' initiation in the workpiece due to the grains’ penetration. For ductile grinding, keeping the uncut chip thickness below the critical chip thickness of the brittle material is necessary. This study focuses on the ductile micro-grinding of Si3N4 as an advanced ceramic and brittle material. The critical chip thickness and the maximum uncut chip thickness were first calculated based on the material properties, the grinding parameters and the microtopography of the utilized grinding pin and then validated by both diamond grit scratches and micro-grinding experiments. Micro-grinding experiments on an inclined workpiece were conducted to investigate the material removal regimes of Si3N4. Grinding forces and surface integrity (surface roughness, surface topography and subsurface damages) induced by different micro grinding parameters and micro-grinding of an inclined workpiece are analyzed in detail. The estimated critical chip thickness and measured maximum uncut chip thickness could be used as an exact guide for achieving the ductile micro-grinding mode. The experiments revealed that the material removal mechanism mainly affects the micro-ground surface integrity. The ductile material removal mode induced no detectable subsurface damage and the surface quality deteriorated by the brittle removal mode.