Wear Loss Evaluation of Silicon Nitride-Hexagonal Boron Nitride Composite using Taguchi Method
Sachin Ghalme1,2*, Ankush Mankar3 and Yogesh Bhalerao4
1Depertment of Mechanical Engineering, Sandip Institute of Technology and Research Centre,India
2Department of Mechanical Engineering, Manoharbhai Patel Institute of Engineering & Technology, India
3Department of Mechanical Engineering, VM Institute of Engineering & Technology, India
4Department of Mechanical Engineering, MIT Academy of Engineering, India
Submission: August 10, 2017; Published: August 28, 2017
*Corresponding author: Sachin Ghalme, Sandip Institute of Technology and Research Centre, Nashik (MS), India,
How to cite this article: Sachin G, Ankush M, Yogesh B. Wear Loss Evaluation of Silicon Nitride-Hexagonal Boron Nitride Composite using Taguchi
Method. JOJ Material Sci. 2017; 2(4): 555592. DOI:10.19080/JOJMS.2017.02.555592
Objective: Research in the field of bio-tribology is trying to evaluate biomaterials with minimum wear. Recently Silicon nitride (Si3N4) is suggested as an alternative for hip/knee joint replacement. With the addition of hexagonal boron nitride (hBN) in Si3N4, its wear properties can be improved.
Methods/Analysis: In this paper, an attempt has been made to evaluate the sliding wear behavior of Si3N4-hBN composite against alumina and steel (ASTM 316L) so as to minimize its wear loss. An attempt has been made to find the effect of hBN addition on wear performance of Si3N4. The experiments were conducted according to Design of Experiments (DoE)-Taguchi method to evaluate the effect hBN addition.
Findings: Taguchi analysis presents 15N load and 8% volume of hBN against alumina, while 15N load and 12% volume of hBN against steel is optimum to minimize wear loss of Si3N4.
Biomaterials in body environment are expected to work satisfactorily, where the pH value of body fluid varies from 1 to 9. Friction, wear, and lubrication of artificial joints are an important consideration to optimise the performance of these man-made joints to improve its function and life. The first metal-on-metal (CoCr-CoCr) total hip replacement (THR) was unsatisfactory because of high friction forces and high rate of wear. Titanium alloys and stainless steel are frequently used in THR. The main risk with metal alloy implants is the release of metal ions due to wear and which creates an adverse effect like aseptic loosening. Therefore metal-on-UHMWPE bearing became advantages or preferable to the metal-on-metal system. Ceramic bearings were first introduced as alternatives to polyethylene (PE) bearings in THR about a decade after Sir John Charnley introduced the first durable THR with a metal-PE articulation. In 1965, the first Al2O3 material dedicated for hip joint was patented, and pioneering application of bio-ceramic was replacing traditional metallic femoral heads of hip prostheses using high density and
pure alumina. The Al2O3 and ZrO2 like oxide have a lengthy history in the field of hip and knee joint replacement providing a tougher bearing surface with low wear rate. Initially, in the engineering field, Si3N4 was proposed as a substitute for conventional materials in extreme operating conditions, due to its hardness, excellent chemical and stability under a broad range of temperature, low density, low thermal expansion, high specific stiffness, corrosion resistance, high elastic modulus and low friction properties . Biocompatibility and material properties of Si3N4 have made it attractive alternative in the biomedical field also . Bearings made of ceramics have low wear properties that make them a suitable alternative for total hip arthroplasty (THA) and total knee arthroplasty (TKA). When compared to cobalt chrome (CoCr)-on-polyethylene (PE) articulations, ceramics offer drastic reductions in bearing wear rates. Alumina and zirconia ceramics are familiar with the orthopaedic field in total joints for several decades . Currently, Si3N4 is applicable in the biomedical field for various applications like bearing forspine disc surgery and prosthetic hip and knee joints also been
developed with Si3N4 [4,5]. Bal & Rahaman  covered scientific
rationale for the use of Si3N4 in the orthopaedic application.
Hexagonal boron nitride (hBN) is solid situ lubricating
material with biocompatibility [7-9]. Incorporating solid
lubricant in Si3N4 can be considered for improving the tribological
performance of Si3N4 by the formation of an oxide of hydrated
layers (H3BO3 and BN(H2O)x) has a significant effect on the
tribological performance of Si3N4-BN composites, reducing the
wear coefficient. Carrapichano et al.  conducted sliding
wear test on pin-on-disc tribometer for Si3N4-BN composite
in a self-mated pair, with 10, 18 and 25% vol. of BN in Si3N4.
They concluded that addition of Boron up to 10% improved
tribological properties of Si3N4 and further addition affect to
mechanical properties of Si3N4. Chen et al.  investigated
sliding wear behaviour of the Si3N4-hBN composite with 0, 5,
10, 20 and 30 volume % of hBN in Si3N4 against Si3N4 using pinon-
disc (PoD) tribometer. They reported that friction coefficient
reduces up to 0.19 for 20% volume of hBN in Si3N4.
Taguchi method is a form of DOE developed by Genichi
Taguchi used for planning experiments and to investigate how
different parameters affect the mean and variance of a process
performance characteristic . Ferit et al.  analysed the
wear behaviour of boronised AISI 1040 steel effectively using
DOE-Taguchi design method. Amar et al.  implemented DOETaguchi
design technique to evaluate the tribo-performance of
polyesterhybrid composites. The result presented that glasspolyester
composite without any filler suffers greater erosion
loss than the hybrid composite with alumina filling. Lastly,
the results were optimized using a genetic algorithm. Iihan &
Suleyman  optimised turning parameters in CNC turning
using Taguchi method and response surface analysis, presented
efficiency and effectiveness of Taguchi method in the field of
optimization. The experimental design proposed by Taguchi
involves the use of orthogonal arrays to organize the control
factors affecting the process and the levels at which they should
be varied. It allows for the collection of the necessary data to
determine which factors affect product quality significantly with
a minimum number of experiments, saving time and resources.
With knowledge of a number of parameters and the number
of levels, the proper orthogonal array can be selected. The
parameters /factors and their corresponding levels selected for
the experiment as shown in Table 1.
Load and % volume of hBN are two factors chosen at five
levels as shown in Table 1. Therefore L25(levelfactor= 52) orthogonal
array selected using Minitab 17 software for conduction of
experiment. The orthogonal array provides a set of well-planned
experiment with the minimum number.
Si3N4-hBN composites prepared with 4, 8, 12 and 16%
volume of hBN mixed in Si3N4. The mixing of Si3N4 and hBN is
performed with a ball mill. The pin samples were prepared at
uni-axial hot-pressing at 30MPa, 1600 °C and 60min dwell time
with dimensions of 10mm diameter and 15mm long. Table
2-4 shows the properties of sintered specimens, properties of
alumina disc and steel disc respectively.
*Testing at Central Glass and Ceramic Research Institute, Kolkata
The wear tests were conducted on Ducom TRLE-PMH400 pin
on disc tribo meter having a maximum normal load capacity of
200N. Tests were performed according to ASTM F732 standards
. During wear test composite used as pin specimen against
alumina disc and steel disc as counter face rotating at a speed
of 200rpm (each test conducted for two times). Tests were
performed at room temperature in a dry environment without
Experiments were carried out on Pin-on-Disc tribo meter
with two input parameters and wear volume loss of a sample asoutput. Wear volume loss calculated for sliding distance covered
by pin during 20min duration and speed of disc 200rpm at
corresponding wear track diameter. Table 5 shows the average
value of volumetric wear loss (VWL) for all 25 experiments (each
experiment conducted two times). The experimental results are
further transformed into Signal-to-Noise (S/N) ratio. Taguchi’s
S/N ratios, which are logarithmic, the function of desired output
and serves as an objective function for optimization. The standard
S/N ratios used are: Smaller is Better (SB), Nominal is Better
(NB), and Higher is Better (HB). The significance of controllable
factor is investigated using S/N ratio approach. A smaller of wear
volume loss is expected to extend joint life. Therefore in this
study S/N ratio with Smaller the Better methodology was used
for wear volume loss and calculated as follow:
y1, y2 and so on = Experimental results/observation.
n= Number of experiments (i……… n).
Irrespective of the category of the performance characteristic,
the higher value of S/N ratio corresponds to a better performance
. The maximization of S/N ratio signifies maximization of
the desired effect against noise factor. In this study minimization
of wear volume loss is a desirable characteristic. Observation
of response table of S/N ratio gives an optimal combination of
input parameters for required output characteristic.
Interaction plot represents interaction effect of control
factors: load and % volume of hBN on performance characteristic
i.e. Volumetric wear loss.
Wear performance of composite against alumina:
Figure 1 shows the minimum value of VWL at the interaction of
15N load and 8% volume of hBN and the maximum value of S/N
ratio at same combination in Figure 2.
Wear performance of composite against steel: Figure 3
shows the minimum value of VWL at the interaction of 15N load
and 12% volume of hBN and the maximum value of S/N ratio at
same combination in Figure 4.
ANOVA is statistically based, objective decision- making
a tool for detecting any difference in average performance of
groups of items tested. It was developed by Sir Ronald Fisher
in the 1930’s as a way to interpret the results from agricultural
experiments . ANOVA is a statistical technique which breaks
total variation down into accountable sources; total variation is
decomposed into its appropriate components. This technique
determines the variability (variance) in data rather than analysis
of data. Table 6 & 7 presents ANOVA table for wear testing against
alumina counter face and steel counter face respectively.
The degree of freedom (DF) is a measure of amount
independent information available from given set of data. DF for
concerning factor is one less than the number of levels.
The sequential or adjusted sum of squares (Seq SS/Adj
SS) of factor measures the variability in data contributed by that
factor. Total SS is SS of an individual factor and SS of error.
Where mean of all observations at ith factor level, mean of
all observations, yij value of jth observation at the ith factor level,
ni number of observations for the ith factor level.
Wear performance of composite against alumina: from
ANOVA table 51.01% contribution is due to combined effect of
load and % volume of hBN while alone % volume of hBN has
25.48% contribution to wear performance.
Wear performance of composite against steel: from
ANOVA table 51.89% contribution is due to combined effect of
load and % volume of hBN while alone% volume of hBN has
35.04% contribution to wear performance.
From the study undertaken on the influence of load and
% volume of hBN addition on the room temperature wearperformance of silicon nitride against alumina and steel, the
following conclusions can be drawn:.
The hBN addition has a significant effect on the wear rate
of silicon nitride sliding against alumina as well as steel
15N load and 8% volume ofhBN volume of hBN in Si3N4 is
the optimum combination to minimize wear rate of Si3N4
against alumina counter face.
15N and 12% volume ofhBN in Si3N4 is the optimum
combination to minimize wear rate of Si3N4 against steel
ANOVA result shows that interaction of load and % volume
of hBN in Si3N4 has a significant effect on wear rate followed
by % volume of hBN.
Si3N4-hBN has proposed an alternative for hip/knee joint
replacement, from experimental analysis it is clear that
suitable combination of load and hBN addition should be
considered for replacement of joint.